Question

Calculate the time required for three-fourths (1/2) of a sample of cesium-100 to decay, given that its half-life is 30.1 minutes

Answer 1

y = (3/4)e^(kt)...
find k.

Answer 2

3/4 of a sample will decay in twice the halflife, or 64.4 minutes. After the first halflife you'll have half left, and after the second you'll have half again, or 1/4, which is 3/4 decay.

Answer 3

how would I find k?

Answer 4

then you can rearrange to solve for t.

Answer 5

to find k, at t=1, only half of your sample of 3/4 is left... and that is 3/8.

Answer 6

ok

Answer 7

so that would be the time required?

Answer 8

what did you get for k?

Answer 9

3?