The key to solving such questions lies with using unit work/hr. Let one man do m work/hr, one boy do b work/hr and one girl do g work/hour. You must be wondering why take work/hour and not work/day or /week. If you see closely, the question itself talks about work hours in a day therefore taking unit as work/hour is the logical choice. If the lowest unit of time had been days I would have taken my variable as work/day. Always take the lowest unit of time as per question.
In 8 days 50 men working 10 hours will do
50*10m*8 = 4000m work
By question we can say, this is also the total work
Now 20 boys and 15 girls would give total work in a day as,
20b + 15g
Their 15 hour work would be
300b + 225g
As boy and girl are equally good and hard working it means b=g
Total work in a day by boy and girl
= 300*b + 225*b = 525b
Now lets say that boys and girls together work for y days to complete the total work. So,
525b*y = 4000m
Y = 4000m/525b
Y= 160/21 (m/b)
The question also tells that m/b =2 (Each works half as hard as a man)
So, y = 320/21 = 15.24
Therefore, they have to work till 15.24 days
In 8 days 50 men can do a job working 10 hr per day. If 20 boys and 15 girls work 15 hr per day, in how many days can the job be completed. Given boys and girls work equally hard and each of them works half as hard as a man
This is reply by AI
The key to solving such questions lies with using unit work/hr. Let one man do m work/hr, one boy do b work/hr and one girl do g work/hour. You must be wondering why take work/hour and not work/day or /week. If you see closely, the question itself talks about work hours in a day therefore taking unit as work/hour is the logical choice. If the lowest unit of time had been days I would have taken my variable as work/day. Always take the lowest unit of time as per question.
In 8 days 50 men working 10 hours will do
50*10m*8 = 4000m work
By question we can say, this is also the total work
Now 20 boys and 15 girls would give total work in a day as,
20b + 15g
Their 15 hour work would be
300b + 225g
As boy and girl are equally good and hard working it means b=g
Total work in a day by boy and girl
= 300*b + 225*b = 525b
Now lets say that boys and girls together work for y days to complete the total work. So,
525b*y = 4000m
Y = 4000m/525b
Y= 160/21 (m/b)
The question also tells that m/b =2 (Each works half as hard as a man)
So, y = 320/21 = 15.24
Therefore, they have to work till 15.24 days
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