Question:
A can finish a piece of work in 12 days and B can finish it in 15 days. Working together, they will finish the work in
A can finish a piece of work in 12 days and B can finish it in 15 days. Working together, they will finish the work in
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Add the per-day fractions, then take the reciprocal for the combined time.
Updated On: Jul 8, 2026
- 7 days
- 6 days
- 6 and 2/3 days
- 7 and 1/2 days
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The Correct Option is C
Solution and Explanation
Step 1: One-day work of each.
A does \(\dfrac{1}{12}\), B does \(\dfrac{1}{15}\).
Step 2: Combined one-day work.
\(\dfrac{1}{12}+\dfrac{1}{15}=\dfrac{5+4}{60}=\dfrac{9}{60}=\dfrac{3}{20}\).
Step 3: Total time.
Time \(=\dfrac{20}{3}=6\tfrac{2}{3}\) days.
\[\boxed{6\tfrac{2}{3}\ \textrm{days}}\]
A does \(\dfrac{1}{12}\), B does \(\dfrac{1}{15}\).
Step 2: Combined one-day work.
\(\dfrac{1}{12}+\dfrac{1}{15}=\dfrac{5+4}{60}=\dfrac{9}{60}=\dfrac{3}{20}\).
Step 3: Total time.
Time \(=\dfrac{20}{3}=6\tfrac{2}{3}\) days.
\[\boxed{6\tfrac{2}{3}\ \textrm{days}}\]
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