- A12 min
- B50 min
- C10 min
- D60 min
Step-by-Step Solution
Net rate = per minute → 60 min. (12 min treats the outlet as an inlet.)
Answer: D) 60 min
An inlet fills a cistern in 20 minutes and an outlet empties it in 30 minutes. If both are opened on the empty cistern, when will it be full?
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