A fraction `f_1` of a radioactive sample decays in one mean life, and a fraction `f_2` decays in one half life. Then

A fraction f_(1) of a radioactive sample decays in one mean lie and a fraction f_(2) decays in one half-life

What fraction of a radioactive sample decay after three half lives?

A certain radioactive sample decays for a time period equal to its mean life . Find (i) the fraction of the sample that disintegrates and (ii) the fraction of the sample that remains intact.