Answer: 60.98%
Step-by-step explanation:
Probability that it is a brand 1 DVD player that needs repair work = Probability of brand 1 DVD needing repairs / Probability that a DVD player will need fixing while under warranty
Probability of brand 1 DVD needing repairs = Brand 1 sales percentage * Percentage of brand 1 needed repair
= 50% * 25%
= 12.5%
Probability that a DVD player will need fixing while under warranty = (50%* 25%) + (30% * 20%) + (20% * 10%)
= 20.5%
Probability that it is a brand 1 DVD player that needs repair work = 12.5% / 20.5%
= 60.98%