Chapter 11 - Probability and Statistics - 11-3 Probability of Multiple Events - Practice and Problem-Solving Exercises - Page 691: 15

$0.54 \text{ or } 54\%$

The formula for the events would be $P(Q and R)=$ $P(Q)$ $\times$ $P(R)$ since the events are independent: $P(Q \space and \space R)=$ $P(Q)$ $\times$ $P(R)$ $P(Q \space and \space R)=$ $0.6$ $\times$ $0.9$ $P(Q \space and \space R)=0.54$ $P(Q \space and \space R)=54$%