36 boys can do a piece of of work in 49 days how many extra boys should be engaged so that the work may be finish in 21 day explain me please
Answers
Step-by-step explanation:
The answer is 48 boys
Workings/ Method
Step #1: Work out the total number of days to complete the piece of work. Each boy worked 49 days and there were 36 boys.
Days * Boys = Total number of days
49* 36 = 1,764
So it took a total of 1,764 days to complete the piece of work.
Step #2: Work out the total number of boys needed to finish a piece of work in 21 days.
We know Days = 21 and Total number of days = 1,764
So using:
Days * Boys = Total number of days
We get:
21 * Boys = 1,764
Use simple algebra to rearrange and find the number of boys.
Boys = 1,764/ 21 = 84
So 84 boys needed to finish a piece of work in 21 days.
Step #3: Work out how many extra boys would be needed.
84 - 36 = 48
48 boys extra boys are required to complete the piece of work.
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Daniel Ravotti
, Bearing Production Department
Answered January 19, 2019
Ok, lets put some man power planning skills in motion, assuming the boys are working 8H per day to get the job done we will need 49 days multiplied by 8H worked by the 36 boys, so 14,112 MH (Man Hours) to get the job done. Now the question is how much more boys I will need to make the job in 21 days, well working 21 days by 8H per day we will have 168 workable hours, so we most divide the total hours to finish the task 14,112 MH between 168H and it will result that we need 84 men to finish this job, the difference of 84 to make it and 36 we had is 48 extra boys to finish in 21 days. Of course all this assuming all conditions and performances are equal.
Of course there is a mathematical way to do it but I thought is more fun using Planning Analogies as the boys are “working”.
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Stephen Deetlefs
Answered January 19, 2019
If one multiplies 36 boys by 49 days you get a
figure “X” of 1764, where X = the total effort needed to get the job done.
If we then divide X by 21 days we get a figure of 84 boys, which is an extra 48 boys needed to get the job done in 21 days.
method 2
36 boys can do a piece of work in 49 days. How many extra boys should be engaged so that the work may be finished in 21 days?
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5 Answers

Has Kumar
, MSc Financial Mathematics from Global Top 20 Ranked Business School (2010)
Answered January 25, 2019
The answer is 48 boys
Workings/ Method
Step #1: Work out the total number of days to complete the piece of work. Each boy worked 49 days and there were 36 boys.
Days * Boys = Total number of days
49* 36 = 1,764
So it took a total of 1,764 days to complete the piece of work.
Step #2: Work out the total number of boys needed to finish a piece of work in 21 days.
We know Days = 21 and Total number of days = 1,764
So using:
Days * Boys = Total number of days
We get:
21 * Boys = 1,764
Use simple algebra to rearrange and find the number of boys.
Boys = 1,764/ 21 = 84
So 84 boys needed to finish a piece of work in 21 days.
Step #3: Work out how many extra boys would be needed.
84 - 36 = 48
48 boys extra boys are required to complete the piece of work.
49 days=36boys
1day=36x49
21 day=1764/21
21 day=84 boys