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A and B together finish a task in 1.5 days, but A left early and the task took 2 days in all. If A alone could finish the work in 2.625 days, how many days before completion did A leave?
A1.125
B0.625
C0.375
D0.875
Answer & Solution
Correct answer: D. 0.875
1. B's rate = 1/1.5 − 1/2.625 = 2/3 − 8/21 = 6/21 = 2/7 per day; B worked all 2 days = 4/7.
2. Remaining work = 1 − 4/7 = 3/7, done by A at 8/21 per day, taking (3/7) ÷ (8/21) = 9/8 = 1.125 days.
3. A left 2 − 1.125 = 0.875 days before completion.
_Source: RRB Group D CEN-02/2018 PYQ, Q.44._
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