Question:
If 12 pumps can empty a reservoir in 20 hours, then time required by 45 such pumps to empty the same reservoir is ______ hours.
Solution:
Time taken by 12 pumps to empty a reservoir = 20 hr
Time taken by 1 pump to empty the reservoir = 20 × 12 = 240 hr
Hence, time taken by 45 pumps to empty the reservoir = 240/45 = (240×60)/45
= 14400/45 = 320 min
= 5×69 + 20 min
= 5 hour 20 min