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SSC CGL 2023 PYQ — Question 70

SSC CGL - 21 July 2023 - Shift 4 • Quantitative Aptitude • Q70

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A can do a piece of work in 8 days, while B can do it in 18 days. In how many days will the work be completed if they both work on alternate days starting with B?

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Correct answer: A

Explanation

The correct answer is option 1 i.e.  1113\frac{1}{3}.

Let the total work be LCM(8 and 18) = 72 units

Amount of work done by A = 728=9\frac{72}{8} = 9 units

Amount of work done by B = 7218\frac{72}{18} = 4 units

The amount of work completed in 2 days will be 9 + 4 = 13 units

13 units can be completed in 2 days 

⇒ 72 units will be completed in = 72×213\frac{72 × 2}{13}  =  1113\frac{1}{3} days