Two pipes A and B can fill a tank in 6 hours and 8 hours respectivley. If both the pipes are opened together, then after how many hours should B be closed so that the tank is full in 4 hours ?
A3
B8
C8/3
D2/3
Answer:
C. 8/3
Read Explanation:
Total work = LCM(6, 8) = 24
efficiency of pipe A = 24/6 = 4
efficiency of pipe B = 24/8 = 3
let after x hours should B be closed so that the tank is full in 4 hours
4 × 4 + 3 × x = 24
16 + 3x = 24
3x = 24 - 16 = 8
x = 8/3