Question

For a radioactive sample of half life 1 hour, probability of decay of an active nucleus in 2 hours in percentage is . (Write upto two digits after the decimal point.)

Answer 1

The probability of a radioactive atom decaying within its half life is 50%.

Probability of not decaying in 1 hour = 0.5
Probability of not decaying in another 1 hour = 0.5
Therefore, the total probability of not decaying in 2 hrs $=0.5\times 0.5$
$=0.25=25\%$

So, probability of decaying in two hours = $(100-25)\%=75\%$