Question

The sample and h is the half-life, in days, of the substance. A sample contains 60% of its original amount of Fermium-257. The half-life of Fermium-257 is about 100 days. About how old is the sample? 52 days 60 days 74 days 136 days

Answer 1

74 days

Explanation:

The computation is shown below;

The proportion that remains left after d days is

p = (1/2)^(d ÷ 100)

In the case when the proportion is 60%

So,

0.60 = 0.50^(d ÷ 100)

Now

log(.60) = (d ÷ 100)log(.50)

100·log(.60) ÷ log(.50) = d = 74 days