Pipes A, B and C can fill a tank in 30hrs, 40hrs and 60hrs respectively, Pipes A, B and C are opened at 7am, 8am and 10am respectively on the same day. When will the tank be full ?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 ie 9.20 p.m
A = 30
B = 40
C = 60
LCM = 120 [A = 4, B = 3, C = 2]
A was opened at 7 a.m. ⇒ work done per hour = 4 units
B was opened at 8 a.m. ⇒ work done per hour = 3 units
C was opened at 10 a.m. ⇒ work done per hour = 2 units
Units completed by A + B till 10 a.m. = (4×3) + (3×2)
= 12 + 6 = 18 units
work left = 120 - 18 = 102
Time taken = 102/9 = 11hrs 20 min
= 9.20 p.m.