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1) A job is completed by 10 men in 20 days and by 20 women in 15 days. How many days will it take for 5 men and 10 women to finish that work? A) 23 days B) 21 days C) 25 days D) 20 days
Answer & Explanation
Answer: 20 days (Let a man's 1 day's work = x & 1 woman's day work =y.
Then, 10x=1/20 and 20y=1/20.
So x=1/200 and y=1/400.
Therefore,(5men+10 women)'s 1 day's work=(5/200+10/400)=1/20 days
so, they will finish the work in 20 days )
2) 12 children take 16 days to complete a work which can be completed by 8 adults in 12 days. 16 adults started working and after 3 days 10 adults left and 4 children joined them. How many days will it take them to complete the remaining work?A) 8 days B) 4 days C) 6 days D) 7 days
Answer & Explanation
Answer: 6 days (Let 1 child's 1 day's work=x and 1 adult's 1 day's work=y
Then,12x=1/16 or x=1/192 and 8y=1/12 or y=1/96.
Work done in 3 days =(16*1/96*3)=1/2
work left= (1-1/2)=1/2.
(6adults+4 children)'s 1 day's work=(6/96+4/192)=1/12.
1/12 work is done by them in 1 day.
1/2 work is done by them in (12*1/2)=6days.
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3) A,B,C can do a piece of work in 11 days,20days & 55 days respectively, working alone. How soon can the work be done if A is assisted by B and C on alternate days?A) 8 days B) 6 days C) 5 days D) 9 days
Answer & Explanation
Answer: 8 days ((A+B)'s 1 day's work=(1/11+1/20)=31/220
(A+C)'s 1 day's work=(1/11+1/55)=6/55
Work done in 2 days= (31/220+6/55)=55/220=1/4.
Now, 1/4 work is done in 2 days.
Therefore, whole work will be done in (4*2)= 8 days.
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4) A is thrice as good a work as B & takes 10 days less to do a piece of work than B takes. B alone can do the whole work in:A) 10 days B) 11 days C) 12 days D) 15 days
Answer & Explanation
Answer: 15 days (Ratio of times taken by A and B = 1:3
A’s 1 day’s work will be completed by B in 3 days & the difference is 2 days.
If difference of time is 10 days,B takes(3/2*10)= 15 days )
5) A does half as much as work as B in 1/3rd of the time. If together, they take 18 days to complete the work, how much time shall B take to do it?A) 40 days B) 50 days C) 45 days D) 60 days
Answer & Explanation
Answer: 45 days (Suppose B takes x days to do the work.
Therefore, A takes(2*(1/3) *x)=2x/3 days to do it.
(A+B)'s 1 day's work=1/18.
Therefore, 1/x+3/2x=1/18
x =45
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