Question

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?

Answer 1

Suppose, the efficiency of skilled worker=x

The efficiency of semi-skilled workers=y and  

The efficiency of unskilled workers=z

Now, according to the question, we have

5x*20=8y*25=10z*30

100x=200y=300z

x=2y=3z

divide the above equation by 6 and equate to k

x/6=y/3=z/2=k

Thus, the efficiency of skilled, semi-skilled and unskilled worker is 6:3:2.

Now, find out the total work as below:

Total work= 5x*20= 5*6*20=600

Now,  

The efficiency of 2 skilled, 6 semi-skilled and 5 unskilled workers=2x+6y+5z=2*6+6*3+5*2=40

Therefore,  

Time required for 2 skilled, 6 semi-skilled and 5 unskilled workers to build a wall=600/40=15 days