Two pipes A and B can fill an empty tank in 10 hours and 16 hours respectively. They are opened alternately for 1 hour each, opening pipe B first. In how many hours, will the empty tank be filled?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. .
Given:
A fill the tank in 10 hours
B fill the tank in 16 hours
Explanation:
Let the total work be (LCM of 10 and 16) = 80.
Efficiency of A (80/10) = 8 units/hour
Efficiency of B (80/16) = 5 units/hour.
B starts the work,
In 2 hours total work done = 8 + 5 = 13 units/hour.
Work done in 12 hours (13 × 6) = 78 units/hour.
Remainin work = 80 - 78 = 2
Time taken by B to complete 2 units of work = 2/5.
Total time taken = 12 + 2/5 = hours.