Which Unit Made It?

Difficulty: Hard · Topics: Probability, Probability, Conditional Probability

A company makes 600 computers a day: 150 in unit A, 200 in unit B and 250 in unit C. Records show that 4\%, 10\% and 20\% of the computers from units A, B and C are faulty.

A computer taken at random from the warehouse turns out to be faulty. What is the probability that it was made in unit A?