The average banana contains $0\mathrm{.}381g$ of potassium, and $0\mathrm{.}012\%$ of naturally occurring potassium is

${?}^{40}K,$ which has a half$-$life of $1\mathrm{.}248{10}^9$ years and an atomic mass of $39\mathrm{.}964u.$ What is the activity of

a freshly picked pair of bananas?