Chapter 11 - Probability and Statistics - 11-3 Probability of Multiple Events - Practice and Problem-Solving Exercises - Page 691: 14

$\dfrac{9}{34} \approx 26.5\%$

The formula for the events would be $P(Q \space and \space R)=$ $P(Q)$ $\times$ $P(R)$ since the events are independent: $P(Q \space and \space R)=$ $P(Q)$ $\times$ $P(R)$ $P(Q \space and \space R)=$ $\dfrac{12}{17}$ $\times$ $\dfrac{3}{8}$ $P(Q \space and \space R)=\dfrac{9}{34}$ $P(Q \space and \space R)=26.5$%