If an MP3 player is randomly selected from this shipment, what is the probability the player has a defective switch or a defective battery?

Question

In a single shipment of MP3 players 10% had defective switches, 5% had defective batteries, and 2% had both defects.

Answer 1

Suppose 1000 in a batch: 100 with defective switches, 50 with defective batteries, 20 with both. Therefore 80 with only defective switches and 30 with only defective batteries, totalling 110. So probability of either is 110/1000=11%.