Tap A runs 3 liters of water per minute into a bucket that has a total volume of 36 liters. Tap B fills a third of the bucket in 20 mins.
Working together how long will it take both taps to fill the bucket ?  Answers:
A) 10 minutes  B) 1.5 hours  C) 9 hours and 12 minutes  D) 15 hours  E) 1 hour and 48 minutes .

Rationale: pipe a has a rate of 3 liters per minute which equals a rate of 180 liters per hour . pipe b has a rate of 36 liters per hour . 180 + 36 ( a + b ) = together they have a rate of 2000 liters per hour . 36 ( the bucket ) / 216 = 1 / 6 = 10 minutes answer - a
Answer: A