Aptitude - Time and Work
11.
A can do a piece of work in 10 days and B can do it in 20 days. They start the work together. But, after 5 days, A leaves off. B will do the remaining work in
Answer
(A + B)'s 5 day's work = 5 x
110 + 120 
= 34
Remaining work = 1 − 34 = 14
120 work is done by B in 1 day
14 work is done by B in 20 x 14 days = 5 days
Answer :
Option AExplanation :
(A + B)'s 5 day's work = 5 x
110 + 120 = 34Remaining work =
1 − 34 = 14120 work is done by B in 1 day
14 work is done by B in
20 x 14 days = 5 days 12.
If 12 men and 16 boys can do a piece of work in 5 days, 13 men and 24 boys can do it in 4 days, then the ratio of the daily work done by a man to that of a boy, is :
Answer
Let 1 man's 1 day's work be x and 1 boy's 1 day's work be y
Then,
12x + 16y = 15 ....(i)
13x + 24y = 14 ....(ii)
Solving (i) and (ii) we get x = 1100 and y = 1200
Required ratio = 1100 : 1200 = 2 : 1
Answer :
Option AExplanation :
Let 1 man's 1 day's work be x and 1 boy's 1 day's work be y
Then,
12x + 16y = 15 ....(i)
13x + 24y = 14 ....(ii)
Solving (i) and (ii) we get x = 1100 and y = 1200
Required ratio = 1100 : 1200 = 2 : 1
13.
To complete a work, A takes 50% more time than B. If together they take 18 days to complete the work, how much time shall B take to do it ?
Answer
Suppose B takes x days. Then, A takes 150100x days, i.e 3x2 days.
∴ 1x + 23x = 118 ⇒ 53x = 118 ⇒ 3x = 90
⇒ x = 30
Hence, B takes 30 days.
Answer :
Option AExplanation :
Suppose B takes x days. Then, A takes 150100x days, i.e 3x2 days.
∴ 1x + 23x = 118 ⇒ 53x = 118 ⇒ 3x = 90
⇒ x = 30
Hence, B takes 30 days.
14.
Kunal can do a work in 15 days. Bimal is 50% more efficient than Kumal. The number of days, Bimal will take to do the same piece of work, is
Answer
Kunal's 1 day's work = 115
Bimal's 1 day's work = 150% of 115 = 110
∴ Bimal can finish the work in 10 days.
Answer :
Option AExplanation :
Kunal's 1 day's work = 115
Bimal's 1 day's work = 150% of 115 = 110
∴ Bimal can finish the work in 10 days.
15.
9 men working 7 hours a day can complete a piece of work in 15 days. In how many days can 6 men working for 9 hours a day, complete the same piece of work ?
Answer
(9 x 7) men working 1 hr a day can finish the work in 15 days.
63 men can finish it in 15 days
1 man can finish it in (15 x 63) days
(6 x 9) men can finish it in 15 x 636 x 9 days = 352 days = 17.5 days
Answer :
Option DExplanation :
(9 x 7) men working 1 hr a day can finish the work in 15 days.
63 men can finish it in 15 days
1 man can finish it in (15 x 63) days
(6 x 9) men can finish it in 15 x 636 x 9 days = 352 days = 17.5 days
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