Pipe C can fill a tank in 12 hours and pipe D can fill the same tank in 40 hours. In how many hours both pipe C and D together can fill the same tank?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 120/13 hours
Let the capacity of tank be LCM of 12 and 40 i.e 120
Efficiency = Total work/Time taken
Efficiency of pipe C = 120/12 = 10 Unit
Efficiency of pipe D = 120/40 = 3 Unit
Efficiency of C + D = 10 + 3 = 13 Unit
Time taken to fill the tank by pipe C and D together = 120/13 hours.