Question

If two pumps are independently selected, what is the probability that neither contains a flaw?​

Answer 1

Answer:

Say the rate of the faster pump is x pool/hour, then the rate of the slower pump would be x/1.5=2x/3 pool/hour.

Since, the combined rate is 1/4 pool/hour, then we have that x+2x/3=1/4 --> x=3/20 pool hour.

The time is reciprocal of the rate, therefore it would take 20/3 hours the faster pump to fill the pool working alone.

Answer 2

Answer:

1/2 is the answer when neither contains a flaw in any one of two so that was the answer.