Answer
$P(\text{Handgun or Rifle or Shotgun})=0.530$
If we select 1000 murder cases in 2009, we would expect about 530 to be resulted from a handgun, rifle, or shotgun.
Work Step by Step
$P(\text{Handgun or Rifle or Shotgun})=P(Handgun)+P(Rifle)+P(Shotgun)=0.473+0.026+0.031=0.530$
This is the Addition Rule for Disjoint Events.
