Question

The average life of a radioactive element is $7.2$min. Calculate the time interval (in min) between the stages of $33.33$% and $66.66$% decay.

Answer 1

As we know, $t_{avg.}=1.44\times t_{1/2};t_{1/2}=5$ min.
Time interval between the stages of 33.33% and 66.66% decay is half life so time is 5min.