alleryPipes fill a tank in 8 and 12 hours. Both open for 2 hours, then the first closes. The second needs more
A6 hours
B9 hours
C7 hours
D8 hours
Answer & Solution
Correct answer: C. 7 hours
Two hours fill 2 x 5/24 = 5/12; the remaining 7/12 at 1/12 per hour takes 7 hours.
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