Quantitative Aptitude • Time, Speed & WorkEasy
A can finish a piece of work in 20 days and B can finish it in 30 days. How many days will they take working together?
A. 10 days
B. 50 days
C. 12 days✓ Correct Answer
D. 25 days
💡 Solution & Explanation
In one day A does 1/20 of the work and B does 1/30. Together they do 1/20 + 1/30 = 1/12 of the work per day. So the whole work takes 12 days. Shortcut: ab ÷ (a + b) = 600 ÷ 50 = 12. Together they must be faster than either one alone.
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