Question 66

A, B and C can individually complete a task in 24 days, 20 days and 18 days, respectively. B and C start the task, and they work for 6 days and leave. The number of days required by A alone to finish the remaining task, is:

Solution

Let the total taskj be 360.

($$\because$$ LCM of 24, 20 and 18 is 360.)

Efficiency of A = 360/24 = 15

Efficiency of B = 360/20 = 18

Efficiency of C = 360/18 = 20

Task done by B and C in 6 days = total efficiency $$\times$$ time = (18 + 20) $$\times$$ 6 = 228

Remaining Task = 360 - 228 = 132

Time taken to complete remaining task by A = work/efficiency = 132/15 = 8 $$\frac{12}{15}$$ = 8 $$\frac{4}{5}$$

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