alleryA and B take 10 days, B and C take 15 days, A and C take 12 days. All three together take
A9 days
B6 days
C7.5 days
D8 days
Answer & Solution
Correct answer: D. 8 days
Twice the combined rate is 1/10 + 1/15 + 1/12 = 1/4, so the three together do 1/8 per day.
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