Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
If 6 men and 8 boys can do a piece of work in 10 days while 26 men and 48 boys can do the same work in 2 days, then the time taken by 20 men for doing the same piece of work will be:
4 days
5 days
2 days
3 days
5 days
Equate the total man-days for both conditions to find the efficiency ratio between a man and a boy, then substitute into the work equation.
6 men and 8 boys can do a work in 10 days; 26 men and 48 boys can do the same work in 2 days
Total┬аWork=(6M+8B)├Ч10=(26M+48B)├Ч2
Equate the total man-days for both conditions to find the efficiency ratio between a man and a boy, then substitute into the work equation.
Confusing man-days with individual daily efficiencies. Always equate total work (Men ├Ч Days + Boys ├Ч Days) across different groups.
Set up the work equation
Let 1 man's 1 day work be M and 1 boy's 1 day work be B. Total work is given by the product of workers and days.
(6M+8B)├Ч10=(26M+48B)├Ч2
Simplify to find efficiency ratio
Expand and simplify the equation to find the relation between the efficiency of a man and a boy.
60M+80B=52M+96BтЯ╣8M=16BтЯ╣M=2B
Calculate Total Work
Substitute M=2B (or in terms of men) into the first condition to get total work units.
Total┬аWork=(6(2)+8)├Ч10=200┬аman-days
Find time taken by 20 men
Divide the total work by the capacity of 20 men.
Days=20200тАЛ=5┬аdays
B is correct because the calculated time taken by 20 men to complete the work is 5 days.
This method of equating man-days is also extremely useful in solving pipe and cistern problems involving different capacities of inlet and outlet valves.
Get instant step-by-step AI explanations, full shift Previous Year Papers (SSC GD, RRB, SSC JE), and regional rank analysis on the official Examoogle App.
Free Download тАв 100K+ Aspirants