A can do a work in 15 days and B in 20 days. If they work together for 4 days, what fraction of the work is left?
A1/15
B7/15
C8/15
D11/15
Explanation
A’s 1-day work = 1/15, B’s 1-day work = 1/20. Together in 1 day = 1/15 + 1/20 = 7/60. In 4 days = 4 * (7/60) = 7/15. Fraction left = 1 – 7/15 = 8/15.
Exam Relevance
- Topic: Work and Time
- Subtopic: Work Done Fraction

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