Concept: The question tests on Rates(Time and Work)
Solution:
Using the options which are give, we can get to the answer. The filling capacity is 10 less than the emptying capacity
Option A: Eliminated as the filling capacity is 0
Option B: Filling Capacity = 45 - 10 = 35 (This can be eliminated as 3600/35 is not an integer)
Option C: Filling Capacity = 50. Emptying time = 3600/60 = 60 minutes and filling time = 3600 / 50 = 72 minutes
The difference = 72 - 60 = 12 minutes (This should be our answer)
You may try the other 2 options in a similar manner.
Option D: Filling Capacity = 80. Emptying time = 3600/90 = 40 minutes and filling time = 3600 / 80 = 45 minutes.
Difference = 45 - 40 = 5 minutes
Option E: Filling Capacity = 90. Emptying time = 3600/100 = 36 minutes and filling time = 3600 / 90 = 40 minutes.
Difference = 40 - 36 = 4 minutes
Option C