Answer:
7.5 hours
Explanation:
half life is the a period of time the sample takes to be half the amount it started the period with
it means we can express it as
original amount / (2^n) = current amount
where n is the number of periods
in the problem if we put 100 / (2^n) = 6.25
we will find that n = 4
we divide 30 over 4 and we get that half life of each period will be equal to 7.5
