SSC CGL 2022 PYQ — Question 64

The correct answer is 2 i.e. $9{{1} \over 3}$

Concept Used:

$Efficiency = {total\ work \over number\ of\ days}$

Explanation:

Let the total work done be LCM of (11, 20, 55) = 220 units.

Now, efficiency of A = ${220 \over 11} = 20\ units/day$

Efficiency of B = ${220 \over 20} = 11\ units/day$

Efficiency of C = ${220 \over 55} = 4\ units/day$

According to the given question, work done is as follows

(B + A) + (B + C) + (B + A) + (B + C)....so on

So, work done in 2 days = (11 + 20) + (11 + 4) = 46 units

Then, work done in (2 × 4) = 8 days = (46 × 4) = 184 units

Now (B + A) work for 1 day, work done in 9 days = 184 + 31 = 215 units

Remaining work to be done = 220 - 215 = 5 units

So, (B + C) complete 15 units in one day, they will complete 5 units in $1\over3$ days.

Hence the total time taken to complete the whole work is $9{{1} \over 3}$ days.