- A70 minutes
- B8 minutes
- C48 minutes
- D35 minutes
Step-by-Step Solution
Q's rate = 1/20 − 1/28 = 7/140 − 5/140 = 2/140 = 1/70 of the cistern per minute, so Q alone takes 70 minutes.
Answer: A) 70 minutes
Taps P and Q together fill a cistern in 20 minutes. Tap P alone would need 28 minutes. How long would tap Q take on its own?
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