An isotope has a half life of 15 hours. A sample of this has a mass of 2 g. Find the mass that remains of t hours.

I tried it but I keep getting 15 and the answer is -1/15

Question

An isotope has a half life of 15 hours. A sample of this has a mass of 2 g. Find the mass that remains of t hours. 

I tried it but I keep getting 15 and the answer is -1/15

anonymous · Answer

just type half life into google and you should be able to find a good tutorial.

anonymous · Answer

this is math section

anonymous · Answer

its a question from my calculus homework

anonymous · Answer

i totally forgot lol...its differential equations right

anonymous · Answer

no, I have to find t, and my book says the answer is t=-1/15, but when I do the equation I get 15. Can I post what I did and you see what I'm dong wrong

anonymous · Answer

$$Y = Ce ^{kt}$$

anonymous · Answer

yea, thats a version of the equation i used. Can you check my steps and see what I'm doing wrong

anonymous · Answer

c is intial value of y
e is just e...you know wht i am talking about
k is proportionality constant (for decay k<0)
and t is time