Thread: Question on a formula - half-life and lamda related

First, hello. this is my first post. I am a mature student studying science.

I'm sure this is very basic, but if anyone can help I'd be very glad.

This is radioactive decay related. I need a formula to calculate from the half-life of a source material, when will there be only 1/9 of it left. The amount of time. I'm rearranging ln and λ but getting a bit confused.

Please let me know if you need more information.

Many thanks.

Jack

Thanks so much. I sort of half get it. Could you possibly give an example of the equation with inputed numbers, stating first what each number represents? Will be much clearer for me then.

I'm a real novice at the moment, so apologies and thanks.