# Quantitative Reasoning – Practice – How long does it take for them to build the wall!

PSA_LEVEL-UP_QNR8) 5 skilled workers can build a wall in 20days; 8 semi-skilled workers can build a wall in 25 days; 10 unskilled workers can build a wall in 30days. If a team has 2 skilled, 6 semi-skilled and 5 unskilled workers, how long will it take to build the wall?

(A) 20 days
(B) 18 days
(C) 16 days
(D) 15 days

Ans:
5 skilled workers can build a wall in 20 days. Therefore, 1 skilled worker can build the same wall in 20*5 or 100 days.

8 semi- skilled workers can build a wall in 25 days. Therefore, 1 semi-skilled worker can build the same wall in 25*8 or 200 days.

10 unskilled workers can build a wall in 30 days. Therefore, 1 unskilled worker can build the same wall in 30*10 or 300 days.

Let us assume, the wall consists of 600 units of work.

Skilled worker’s one day work= 600/100 = 6 units

Semi-skilled worker’s one day work= 600/200 = 3 units

Unskilled worker’s one day work= 600/300 = 2 units

Since, the team has 2 skilled, 6 semi-skilled and 5 unskilled workers, team’s one day work

= 2*6 units + 6*3 units + 5*2 units

= 12 + 18 + 10 = 40 units.

Thus, to complete 600 units at the rate of 40 units per day, it will take 600/40 or 15 days. Option D.