A is twice as efficient as B and can finish a job in 20 days less than B. In how many days can they complete the work together? MCQ with Answer and Explanation
A is twice as efficient as B and can finish a job in 20 days less than B. In how many days can they complete the work together?
A. 13(1/3) days
B. 15 days
C. 14(2/3) days
D. 12 days
Answer: Option A
Solution (By JKSSB Mock Tests)
Efficiency ratio A : B = 2 : 1. Time ratio A : B = 1 : 2. Difference = 1 part = 20 days. So A takes 20 days and B takes 40 days. Total work = 40 units. Combined efficiency = 3. Time taken together = 40 / 3 = 13(1/3) days.
Explanation:
Ratio of work done by A and B = 2:1. Let B's 1-day work be x, so A's 1-day work is 2x. Together, 3x = 1/18, which means x = 1/54. A's 1-day work = 2 * (1/54) = 1/27. Thus, A alone completes it in 27 days.
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