Chapter 11 - Probability and Statistics - 11-3 Probability of Multiple Events - Practice and Problem-Solving Exercises - Page 691: 13

$\dfrac{1}{6}$ or $16.\overline{6} \%$

The formula for the events would be $P(Q \space and \space R)=$ $P(Q)$ $\times$ $P(R)$ since the events are independent: $P(Q \space and \space R)=$ $P(Q)$ $\times$ $P(R)$ $P(Q \space and \space R)=$ $\dfrac{1}{4}$ $\times$ $\dfrac{2}{3}$ $P(Q \space and \space R)=\dfrac{2}{12}=\dfrac{1}{6}$ $P(Q\space and \space R)=16.\overline{6}\%$