Mathematics
NULL
Medium
Question
P alone takes as long as Q and R together. P and Q finish in 10 days; R alone needs 50 days. How long does Q alone take?
A
30 days
B
25 days
✓ Official correct answer
C
20 days
D
15 days
Community credibility
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A
30 days
No member explanations yet for this option.
B
25 days
No member explanations yet for this option.
C
20 days
No member explanations yet for this option.
D
15 days
No member explanations yet for this option.
Explanation
Since P = Q+R, 2P = P+Q+R = 1/10 + 1/50 = 3/25 ⇒ P = 3/50. Then Q = 1/10 − 3/50 = 1/25 ⇒ 25 days.