Chapter 29, Problem 55P

To determine

The number of $\text{K}$ nuclei in a body with half-life equal to $1.28\times {10}^9\text{years}$. The total beta energy absorbed in a year is $\text{9}\text{.68}\times {\text{10}}^{-3}\text{J}$, the mass of body is $80\text{ kg}$ and $1.4\text{MeV}$ of energy is deposited per decay.