Question

Please help! A material decays at a rate of 1.1% per year. If you start with 250 grams of the material, in how many years will there be 100 grams remaining? Round to one decimal place. What equation correctly models the situation?

Answer 1

100=250(1-1.1/100)^T
Now solve

Answer 2

It's an exponential decrease so just use it

Answer 3

By dividing both sides by 250 first?

Answer 4

yeap

Answer 5

.4=.989^t?

Answer 6

Now take log on both sides

Answer 7

T=(ln 0.4/ln.989)

Answer 8

Yay I did it right :) Thank you roshan2004.

Answer 9

Most welcome mate!