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Thread: Mistakes?

  1. #1 Mistakes? 
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    I took and test and failed it. I had to get 12/15 correct on this internet test but I think they F'd up on a few problems. I don't get any of the answers given. If you guys do tell me how you got your answer.



    4. George paid $31.25 in taxi fare from the airport to the hotel. The cab charged $3.75 for the first mile plus $2.50 for each additional mile. The equation to find the number of miles, m, from the airport to the hotel would be: *
    3.75 + 2.50m + 31.25 = 37.50

    3.75 + 2.50m = 31.25

    1.25 + 2.50m = 31.25

    31.25 + 3.75 = 2.50(m-1)




    3. What is the value of x in the equation? (x/3)+(2x/7)=3(2/21)

    3

    5

    7

    9




    13. A boat cruises downstream for 2 hours before heading back. It takes 3.5 hours going upstream to get back. If the speed of the stream is 8 mph, what is the speed of the boat in still water?: *
    14.7 mph

    19.6 mph

    24.8 mph

    29.3 mph


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    For problem 4 the answer is

    1.25 + 2.50m = 31.25

    The reason is, you are paying 2.50 per mile plus an extra 1.25 for the first mile and the total is 31.25. The answer is 12 miles.

    For problem 3, I did not get any of the answers given. I got x=6/13

    Problem 13
    Distance = velocity * time
    Distance downstream= ( x+8 )*2 =
    Distance upstream = ( x-8 )*3.5
    16+2x=3.5x-28
    1.5x=44
    x=29.3


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  4. #3 Re: Mistakes? 
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    Quote Originally Posted by EV33
    I took and test and failed it. I had to get 12/15 correct on this internet test but I think they F'd up on a few problems. I don't get any of the answers given. If you guys do tell me how you got your answer.



    4. George paid $31.25 in taxi fare from the airport to the hotel. The cab charged $3.75 for the first mile plus $2.50 for each additional mile. The equation to find the number of miles, m, from the airport to the hotel would be: *
    3.75 + 2.50m + 31.25 = 37.50

    3.75 + 2.50m = 31.25

    1.25 + 2.50m = 31.25

    31.25 + 3.75 = 2.50(m-1)




    3. What is the value of x in the equation? (x/3)+(2x/7)=3(2/21)

    3

    5

    7

    9




    13. A boat cruises downstream for 2 hours before heading back. It takes 3.5 hours going upstream to get back. If the speed of the stream is 8 mph, what is the speed of the boat in still water?: *
    14.7 mph

    19.6 mph

    24.8 mph

    29.3 mph
    You cannot actually answer that last question without an assumption.

    You do not know if the boat was powered with the same power downstream as up.

    So you do not know the distance traveled without an assumption. You may have left something out though.

    However if you did not, this is a question that is not about teaching, but rather to start poor habits.

    Tests are for fifth world nations. American's don't try to do anything they just do it.
    The time you waste making up tests you could use to solve real problems. Of course it will instantly bring you under fire for being a bold powerful American citizen, that obviously sees the shortcomings in law makers.



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    William McCormick
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  5. #4 Re: Mistakes? 
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    Quote Originally Posted by William McCormick
    Quote Originally Posted by EV33
    13. A boat cruises downstream for 2 hours before heading back. It takes 3.5 hours going upstream to get back. If the speed of the stream is 8 mph, what is the speed of the boat in still water?: *
    14.7 mph

    19.6 mph

    24.8 mph

    29.3 mph
    You cannot actually answer that last question without an assumption.

    You do not know if the boat was powered with the same power downstream as up.

    So you do not know the distance traveled without an assumption. You may have left something out though.

    However if you did not, this is a question that is not about teaching, but rather to start poor habits.

    Tests are for fifth world nations. American's don't try to do anything they just do it.
    The time you waste making up tests you could use to solve real problems. Of course it will instantly bring you under fire for being a bold powerful American citizen, that obviously sees the shortcomings in law makers.
    I think I’m going to cut & paste this on all the Internet forums I visit so as to give everybody a good laugh. In fact, I think I’m going to join some new forums just to cut & paste this there and share the joke around.

    In fact, I think I should print this out, frame it and take it with me wherever I go. Then whenever I’m feeling down, I only have to take it out and read it, and my depression will be instantly cured.
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  6. #5  
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    William, don't call sour grapes just because you don't understand high school algebra.
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  7. #6  
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    Darn it. Yea I got the same thing for 3 but I didn't think you could do the other ones, I figured there was something I was missing though.
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  8. #7 Re: Mistakes? 
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    Quote Originally Posted by JaneBennet
    Quote Originally Posted by William McCormick
    Quote Originally Posted by EV33
    13. A boat cruises downstream for 2 hours before heading back. It takes 3.5 hours going upstream to get back. If the speed of the stream is 8 mph, what is the speed of the boat in still water?: *
    14.7 mph

    19.6 mph

    24.8 mph

    29.3 mph
    You cannot actually answer that last question without an assumption.

    You do not know if the boat was powered with the same power downstream as up.

    So you do not know the distance traveled without an assumption. You may have left something out though.

    However if you did not, this is a question that is not about teaching, but rather to start poor habits.

    Tests are for fifth world nations. American's don't try to do anything they just do it.
    The time you waste making up tests you could use to solve real problems. Of course it will instantly bring you under fire for being a bold powerful American citizen, that obviously sees the shortcomings in law makers.
    I think I’m going to cut & paste this on all the Internet forums I visit so as to give everybody a good laugh. In fact, I think I’m going to join some new forums just to cut & paste this there and share the joke around.

    In fact, I think I should print this out, frame it and take it with me wherever I go. Then whenever I’m feeling down, I only have to take it out and read it, and my depression will be instantly cured.
    The boat is going to have to raise itself perhaps a mile or more. That is horse power. When you are talking about a boat that might weigh 500,000 pounds.

    Going up stream. You would need to know if the boat is going the same speed downstream as upstream in order to calculate the difference the height created.

    But you are welcome to post my answer.

    Sincerely,


    William McCormick
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    Also a boat has a sweet spot, its maximum efficiency. In both engine RPM and hull design. So that when you push a boat past a certain speed, its hull is no longer capable of the same efficiency. Unless you can get it into a plane or prop ride.

    The engines, shaft and propeller have an optimum range. You would need to know what the effect of fighting an eight mile an hour current will do to the engine performance.

    So you would need to know the answer to that question in order to answer it.

    I had an International Unlimited ships captain license long before I was eighteen years old, I think I was twelve when I could captain any ship on earth. I just got it so I could captain a vessel in local waters under age. The training and test, was issued by the United States Navy Waves.



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    William McCormick
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  10. #9  
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    William, replace every instance of "boat" with "Billy McC" and every instance of "stream" with "moving sidewalk" and then shut up. The point is: this isn't a question about boats, this is a question about algebra. If you say boat one more time, I'll have to... be rude to you again.
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  11. #10  
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    William McCormick, in case you missed it:

    Quote Originally Posted by Harold14370
    Problem 13
    Distance = velocity * time
    Distance downstream= ( x+8 )*2 =
    Distance upstream = ( x-8 )*3.5
    16+2x=3.5x-28
    1.5x=44
    x=29.3
    If you don’t understand the maths, then just shut up, okay? It’s not your question, and none of your business.

    You have caused enough mischief in the Physics forum. Please keep out of the Mathematics forum.
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    Quote Originally Posted by JaneBennet
    William McCormick, in case you missed it:

    Quote Originally Posted by Harold14370
    Problem 13
    Distance = velocity * time
    Distance downstream= ( x+8 )*2 =
    Distance upstream = ( x-8 )*3.5
    16+2x=3.5x-28
    1.5x=44
    x=29.3
    If you don’t understand the maths, then just shut up, okay? It’s not your question, and none of your business.

    You have caused enough mischief in the Physics forum. Please keep out of the Mathematics forum.

    That will not tell you anything about a boat traveling on a river, at an unknown speed. With a river elevating at an unknown angle.

    Sorry, that is the real world of math.

    If the free speed of the boat is set to eight miles per hour, it will slip downstream, in the river heading up stream against an 8 mile an hour flow. Because a moving river is on an angle.

    You would need to know the elevation of the river, and the effects of hull and drive train at elevated RPM. That is math A+ style.

    Anyone that answered the question right, would probably die on the river, or run out of gas. That is not the purpose of math.

    Yelling in big letters is not the purpose of a math forum.

    Math is a fun calm thing for all.


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    William McCormick
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  13. #12  
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    William,
    you can face a ban, or you can behave yourself. Your choice. I'm running out of patience.
    So we don't misunderstand each other, this is an official warning.
    Ophiolite
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    Here is something I feel strongly about.

    If you were to offer that problem to students, as

    A hobby radio controlled race car on a toy manufacturing conveyor belt, starts up and runs down the very long conveyor for 2 hours.
    Then suddenly turns around and heads up the conveyor for 3.5 hours.
    The car maintains a constant wheel speed.
    The conveyor belt is moving at 8 miles per hour. What was the speed of the car?

    Those that are interested could answer it. And if the teacher called on me I could say "What Harold said"

    I look at it like the river traveled 8 miles an hour for 5.5 hours or 44 miles. Causing a 1.5 hour difference between the two directions.

    Making a ratio of 1.5/5.5 = 44/Total miles. So if you multiply 5.5 by 44 you get 242 and when you divide that by 1.5 you get 161.33333333333333333333333333333 the total miles traveled. By dividing the two fractions you create a 1 divided by 1 scenario and you just fill in the blank by dividing by 1.5

    Then you can get the miles per hour by dividing by 5.5, and check it by dividing 161.3333333 by 1.5 and getting 44.

    But that original question is just to far away from reality for an intelligent individual that actually knows how things work. It is a very poor question. Asking you to make assumptions. Rewarding someone for their assumption.
    That is not math. I could not even imagine what the question was trying solve. This I am totally serious about.

    To truly understand the math though, you have to realize that the difference created in the respective times of travel in each direction, is a concatenation of the miles the river traveled.

    But in real life this equation would not work for a boat.

    I think teachers use tests to hide that they already know that class sucks and not many are learning, by catching the kids flipping them the bird kind of out of the corner of their eye. And the derogatory graffiti on school equipment. Students do not need tests. They need teachers.



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    William McCormick
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  15. #14  
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    Quote Originally Posted by Ophiolite
    William,
    you can face a ban, or you can behave yourself. Your choice. I'm running out of patience.
    So we don't misunderstand each other, this is an official warning.
    Ophiolite
    I just caught your post. Is there something that you can highlight for me about what is not correct for a math forum?

    I am meaning no insult or injury. I would hope math does not hurt anyone.



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    William McCormick
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  16. #15  
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    William: I'll agree with you that, if we wanted to get the real answer to the question, we'd need more information and a more careful analysis. However, let's look at the context of the problem.

    First, this is clearly from an introductory algebra class, so we can assume that the EV33 and his classmates do not have a lot of advanced science under their belt and are thus unlikely to reach the objections that you raise. Asking for a more detailed answer than the one Harold gave is inappropriate.

    Second, problems like this were likely covered in EV33's class, whether in lecture, in the text, or in homework, and the general method of solving these questions in the context of the course was probably covered. So the students probably knew what sort of solution was expected of them in this problem, even if they realized that the problem was more complicated than said solution suggests.

    Third, the point of this problem is not to test the students' understanding of nautical travel. The point of the problem is to test the students' understanding of algebra and its applications, in particular applying simple linear equations in one variable. Asking for anything more detailed than this is asking the student to go beyond the math that they have developed so far.

    So your complaints really aren't relevant to the discussion at hand, as you're ignoring the context of the problem. Feel free to open up a new thread about the nature of boats moving through moving water, but understand that you have once again ruined a discussion due to your missing the point.
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    Quote Originally Posted by serpicojr
    William: I'll agree with you that, if we wanted to get the real answer to the question, we'd need more information and a more careful analysis. However, let's look at the context of the problem.

    First, this is clearly from an introductory algebra class, so we can assume that the EV33 and his classmates do not have a lot of advanced science under their belt and are thus unlikely to reach the objections that you raise. Asking for a more detailed answer than the one Harold gave is inappropriate.

    Second, problems like this were likely covered in EV33's class, whether in lecture, in the text, or in homework, and the general method of solving these questions in the context of the course was probably covered. So the students probably knew what sort of solution was expected of them in this problem, even if they realized that the problem was more complicated than said solution suggests.

    Third, the point of this problem is not to test the students' understanding of nautical travel. The point of the problem is to test the students' understanding of algebra and its applications, in particular applying simple linear equations in one variable. Asking for anything more detailed than this is asking the student to go beyond the math that they have developed so far.

    So your complaints really aren't relevant to the discussion at hand, as you're ignoring the context of the problem. Feel free to open up a new thread about the nature of boats moving through moving water, but understand that you have once again ruined a discussion due to your missing the point.
    The way I posted the question would be the correct way to put the question forward. If there is any validity to just wanting to teach algebra?

    But when you bring home the hobby car problem, dad is going to say what the hell are you going to do with that? I always told pop the stupid teachers give you this stuff.

    I don't see the importance or the benefit to letting kids think they calculated a boat or ships speed, from the time it traveled up and down a river.

    I don't know that you can, exactly. Given changing wind speed and areas not effected by wind. The position of the boat in the river plays a part. At the sides of the river it often slows. Or can positively accelerate (go faster). The same is true of the center of the river.

    I am not condemning algebra, I am condemning the methods used to teach it.

    You have to be able to understand why the boat takes a longer time to travel upstream then downstream. And you need to understand the ratio at work. Or you are just guessing at the right formula to use. This happens in real life everyday now. College engineers, use a memorized formula to get an answer to an unrelated problem.

    It is evident to them that school has failed them, they tend not to discuss it, with others. When you ask them how they came to the conclusion, they do not wish to discuss it honestly. And when the working man reports the honest truth back they do not wish to hear it either.

    An honest working man will tell exactly his steps to create the error. Quickly, and in a way so as not to cause another compounded error.

    I am totally one hundred and ten percent sure that today's engineers totally misunderstand how to use formulas. But they can recite the formulas from memory. And even explain their origin and history. Remarkable.

    I do not even remember pi R^2 unless I think about it. And what it does. By multiplying the radius by itself, you get the area of a quarter of a square that would circumscribe the circle we are trying to get the area for. The ratio of area of the circle to the square must be 3.14/4

    The only way is to look at the boat problem is from all angles. And lastly and least important try to get kids to remember math formulas that are little used in real life, to do great things.

    I had to look, and work on the boat problem before I understood the ratio and what caused it.



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    William McCormick
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  18. #17  
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    William,
    you are really trying my patience to the extreme. Just because you believe the world of science and engineering is totally screwed up I see no need for you to make certain that productive discussions on this forum are totally screwed up. Your behaviour is rude and anti-social. Your divergent opinions are now well understood by regular participants on the forum. You do not need to interject them at every opportunity. They are not welcome.

    You are welcome, but only when you adhere to the norms of this particular social group. That is the way the world works. I am not interested in hearing a long diatribe about why I should be interested and about how screwed up we are. Go tell it to the daffodils. Keep on topic in a manner that befits the intent of this forum as expressed by the majority of members.
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  19. #18  
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    Quote Originally Posted by William McCormick
    If there is any validity to just wanting to teach algebra?
    Yes, because algebra is useful in a variety of contexts.

    I don't see the importance or the benefit to letting kids think they calculated a boat or ships speed, from the time it traveled up and down a river.

    I don't know that you can, exactly.
    Well, fuck, if nobody can exactly calculate the boat's speed, then what's the harm in having the kids apply their algebra to a simplification of the problem?
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    Quote Originally Posted by serpicojr
    Quote Originally Posted by William McCormick
    If there is any validity to just wanting to teach algebra?
    Yes, because algebra is useful in a variety of contexts.

    I don't see the importance or the benefit to letting kids think they calculated a boat or ships speed, from the time it traveled up and down a river.

    I don't know that you can, exactly.
    Well, fuck, if nobody can exactly calculate the boat's speed, then what's the harm in having the kids apply their algebra to a simplification of the problem?
    Because it would be like giving them a hammer, and saying, beat on this tree here, and you are practicing carpentry. It would be an insult to their intelligence, as well as the teachers intelligence.

    The problem is teachers get a degree, having never really done all the things the algebra would be used on. They get the summer off with pay and believe that they are the chosen ones. They also tend to believe carpenters and workers are stupid people beating on things with a hammer. When the almost exact opposite it true. Teachers tend to beat on children with their poor teachings.

    If teachers learned how to apply algebra to real fields they would also learn that men are needed badly to take back control of a society in a suicidal spin.


    The algebra in the case of the river trip is almost totally done by reality, by the ratio of time to distance traveled and how it works out naturally, on a hypothetical river trip.

    That is what they should be tested on. Understanding what they want to apply algebra too. I see this everyday. Awesome applications of algebra. I wouldn't even take a stab at it. Mostly because the overall project does not interest me.
    But the project when finished is in the wrong place, below the water table, made out of the wrong material. It collapses under its own weight. The foundations are not strong enough. But the math or algebra is accurate or understood?

    I am not anti social, I am anti giant education grinding wheel. Education is to the point of "do not question, remember or fail".

    I used to ask questions like "wouldn't the boat change speed and veer from an exact center path in the river? Wouldn't the river have currents and eddies? And what about the wind?
    Until I had the teacher at the hobby car on the 5.5 mile conveyor belt. And then I would say, what do I need that for? And she would excuse me.

    But would they come in with real life stuff, nope. Just more book stuff to remember. Only the industrial Arts teachers and science teachers, had reality pretty well covered. With the does and do not's, and with all the nasty little dangers. Explosions, fires, poison gas, cut off fingers. Ha-ha.

    Do you know what they did to those classrooms and funding. They cut them out almost totally.

    I will give you an example, cutting birds mouth rafters for a house or a dog or bird house. A small boy could easily learn to lay them out, most of us live in a house or would like to. Does anyone teach a small boy how to lay them out. Or how to apply algebra to the task. No. Because most teachers cannot lay them out. Or even get interested in them. Or show pictures of their rafters and project. Yet that is a basic application of algebra.

    A carpenter applies basic algebra so fast that you would not even believe that he is using algebra or how often in a five second tally. But he is.

    The same is true of every profession. What would be called tricks are often just basic applications of algebra. They go overlooked and many believe that they cannot use algebra because they have only been shown abstract algebra, that does not relate to the natural day to day applications where algebra would shine. Most complicated algebra probably belongs in the back of a Sudoku game puzzle. Not in a classroom for life and learning.

    But I do understand the amazement of algorithms, and algebra to get the answers to mind bending problems with a short calculation. However that is anti productive when basic algebra is lacking. Complex algebra is often introduced when basic teaching is not going well. The teacher tends to show boat esoteric or little used formulas or procedures to gain interest from the class.





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    William McCormick
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  21. #20  
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    William,
    you should be old enough and wise enough to not only know, but to understand concepts such as 'walk before you can run', 'don't bite off more than you can chew', etc. When we teach children to read they first learn the letters of the alphabet. They learn simple sentence: the cat sat on the mat. They learn simple vocabulary. Later, the well educated, informed and intelligent individual may utilise an extensive vocabulary, within complex, lengthy structures, employing a variety of syntactical and lexical devices, to make their point.
    You seem blissfully unaware of this. Your position on the matter wholly lacks the practicality you claim to be so important. Your attempt at responding to reality actually places you in a theoretical swamp, surrounded by the miasmal mists of confusion.
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    I'd be happy to continue this discussion in the education forum. You're off topic and out of bounds with respect to the math forum.
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