Mathematics
NULL
Medium
Question
P takes twice as long as Q and thrice as long as R to finish a work. Together they finish in 2 days. How long does Q take alone?
A
7
B
8
C
9
D
6
✓ Official correct answer
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A
7
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B
8
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C
9
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D
6
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Explanation
Let Q take 3x, R take 2x, P take 6x. Then 1/(6x) + 1/(3x) + 1/(2x) = 1/2 ⇒ 1/x = 1/2 ⇒ x = 2. Q takes 6 days.