Farjan and Kashif can complete a task in 30 days. Farjan leaves after 20 days and Kashif alone completes it in another 25 days. How many days does Farjan alone take to complete the entire task?
Correct answer: A. 50
- A. 50
- B. 75
- C. 60
- D. 45
Explanation
Together they complete 20 days x 1/30 of the work per day = 2/3, leaving 1/3 for Kashif. Kashif's rate is (1/3) ÷ 25 days = 1/75 of the work per day, so Farjan's rate is 1/30 - 1/75 = 1/50 of the work per day and Farjan alone needs 50 days. Students may choose 75 days by taking Kashif's individual time as Farjan's time.
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About Time and Work
Problems measure work through rates, treating each person's or machine's contribution as work completed per unit time. Questions cover combined work, efficiency, wages, alternate working schedules, pipes and cisterns, and men-days relationships, with care needed to distinguish time taken by one worker from the time required when workers act together.
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