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SSC Selection Post 2020 PYQ — Question 61

SSC Selection Post - Matriculation Level 2020 - 6 Nov 2020 - Shift 1 • Quantitative Aptitude • Q61

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A can finish 353\over5 of a task in 6 days and B can finish 232\over3of the same task in 12 days. A and B worked together for 5 days. C alone completed the remaining task in 8 days. B and C, working together, will complete the same task in:

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Correct answer: C

Explanation

The correct answer is option 3 i.e. 12 days.

Time taken by A to complete the whole work = 6 × 535\over3 = 10 days

Time taken by B to complete the whole work = 12 × 323\over2 = 18 days

LCM(10, 18) = 90

The efficiency of A = 90/10 = 9 units

The efficiency of B = 90/18 = 5 unit

Work done in 5 days = 5(9 + 5) = 5 × 14 = 70 units

Remaining = 90 - 70 = 20 units

The efficiency of C = 208=52{20\over8 }= {5\over2} units

Time taken by B and C = 905+5290\over{5+{5\over2}} = 9015290\over{{15\over2}} = 12 days