Chapter 31, Problem 41P

To determine

To find:The value of $\mathrm{\beta }$ counting rate.

Explanation of Solution

The counting rate will be $85\mathrm{\%}$ of $25\mathrm{\%}$ of the activity.

The $\mathrm{\beta }$ counting rate is

  $\begin{array}{l}\left(0.035\times {10}^{-6}\text{Ci}\right)\left(\frac{3.7\times {10}^{10}\text{ decays }/\text{s}}{1\text{Ci}}\right)\left(\frac{1\mathrm{\beta }}{1\text{ decay }}\right)(0.25)(0.85)\\ =275.18\text{ counts }/\text{s}\approx 275\text{ counts }/\text{s}\end{array}$

The $\mathrm{\beta }$ counting rate is $275\text{ counts }/\text{s}$