Question 3
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A and B together finish a job in 12 days, and A alone in 20 days. How long will B alone take?
- A 8 days
- B 32 days
- C 24 days
- D 30 days Correct
Correct Answer: Option D
B's rate = 1/12 − 1/20 = (5 − 3)/60 = 1/30
B alone = 30 days
Trap: 20 − 12 = 8 subtracts days, not rates.
Answer: 30 days
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