Researchers evaluate a sample of Carbon6 which has a halflif

Researchers evaluate a sample of Carbon-6, which has a half-life of 20 minutes. For a particular sample, they observed that 75% of the original amount of Carbon-6 had decayed. How old is this sample?

Solution

(1/2)ⁿ = 0.25

n log 0.5 = log 0.25

n = log 0.25 / log 0.5

n = 2......so, time = 20*2 =40 minutes....

the sample is 40 minutes old...