Question

Tap a can fill a cistern in 8 hours and tap b can empty it in 12 hours . How long it will take to fill the cistern if both of them are opened together

Answer 1

Given:-

• Tap a can fill a cistern in 8 hours.
• Tap b can empty it in 12 hours.

To Find:-

• Time required to fill the cistern if both of them are opened together.

Solution :-

Tap a can do 1/8 work in 1 hour.

And tap b can do 1/12 work in 1 hour.

So,

Total work done by both the types when they are poened together = work done by tap a + work done by tap b.

Total work = 1/8 + (-1/12)

Total work = 1/8 - 1/12

Total work = 1/24

Hence, 24 hours will be taken by both the taps.