Pipes A and B together fill a tank in 10 hours, B and C in 12 hours, and C and A in 15 hours. How long would A alone take?
Correct answer C. 24 hours
Explanation
2(A + B + C) = 1/10 + 1/12 + 1/15 = 1/4, so A + B + C = 1/8. A = 1/8 − 1/12 (B and C) = 1/24, so A alone takes 24 hours.
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