Time and Work
- Mr. Prashant has to build a wall 1000 meters long in 50 days. He employs 56 men but at the end of 27 days finds that only 448 meters are built. How many men must be employed so that the work may be finished in time?
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Fewer days, more men, more length, more men
Correct Option: C
Y = 56 x (27/23) x (552/448)
=81
Extra men required =81-56
=25
- Mr. Modi can copy 40 pages in 10 minutes, Mr. Xerox and Mr. Modi both working together can copy 250 In 25 minutes. In how many minutes Mr. Xerox can copy 36 pages?
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Efficiency ( per minute) of Modi = 4 copies/min
Efficiency of Modi and Xerox together = 10 pages/min
∴ Efficiency of Xerox alone = 10 - 4 = 6 pages/minCorrect Option: B
Efficiency ( per minute) of Modi = 4 copies/min
Efficiency of Modi and Xerox together = 10 pages/min
∴ Efficiency of Xerox alone = 10 - 4 = 6 pages/min
∴ Mr. Xerox needs 6 min to copy 36 pages.
- 25 men and 15 women can complete a piece of work in 12 days. All of them start working together and after working for 8 days the women stopped working. 25 men complete the remaining work in 6 days. how many days will it take for completing the entire job if only 15 women are put on the job ?
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25 men and 15 women can complete, a piece of work in 12 days.
∴ Work done by them in 8 days = 8/12 = 2/3
Remaining work is completed by 25 men in 6 days
∴ Time taken by 25 men to complete the whole work = 3 x 6 = 18 daysCorrect Option: D
25 men and 15 women can complete, a piece of work in 12 days.
∴ Work done by them in 8 days = 8/12 = 2/3
Remaining work is completed by 25 men in 6 days
∴ Time taken by 25 men to complete the whole work = 3 x 6 = 18 days
From the question
Time taken by 15 women to complete the whole work = 1 / (1/12 - 1/18)
= 1 / {(3 - 2) / 36} = 36/(3 - 2) = 36 days
- A can do a piece of work in 12 days, B can do the same work in 8 days and c can do the same job in 4 / 5 th time required by both A and B. A and B work together for 3 days, then C complete days did C work ?
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As per question, work of A for 1 day = 1/12 and work of B for 1 day = 1/8
∴ Work of (A + B) together for 1 day = 1/12 + 1/8 = (2 + 3)/24 = 5/24
⇒ Work of (A + B) together for 3 days = 3 x (5/24) = 5/8
⇒ Remaining work after 3 days = 1 - 5/8 = 3/8
∵ C can do the same work in = 4/5th time required by (A + B) = 4/5 x 24/5 = 96/25 days
⇒ Work of C for 1 day = 25/96 part.
⇒ 25/96 part work can be done by C in 1 day
⇒ 3/8 part work can be done by C in = 96/25 x 3/8 days = 36/25 days = 111/25
∴ The complete day C did the work = 1 day.Correct Option: D
As per question, work of A for 1 day = 1/12 and work of B for 1 day = 1/8
∴ Work of (A + B) together for 1 day = 1/12 + 1/8 = (2 + 3)/24 = 5/24
⇒ Work of (A + B) together for 3 days = 3 x (5/24) = 5/8
⇒ Remaining work after 3 days = 1 - 5/8 = 3/8
∵ C can do the same work in = 4/5th time required by (A + B) = 4/5 x 24/5 = 96/25 days
⇒ Work of C for 1 day = 25/96 part.
⇒ 25/96 part work can be done by C in 1 day
⇒ 3/8 part work can be done by C in = 96/25 x 3/8 days = 36/25 days = 111/25
∴ The complete day C did the work = 1 day.
- A completes a work in 15 days. B complete the same work in 20 days. A started working alone after 1 days B joined him. How many day will they now take together to complete the remaining work ?
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Work of A for 1 day = 1/15
Work of B for 1 day = 1/20
Work of (A + B) together for 1 day = 1/15 + 1/20 = (4 + 3)/60 = 7/60
Remaining work after A alone does for 1 day = 1 - 1/15 = 14/15
∵ 7/60 part-work can be complete by (A + B) in 1 days
∴ 14/15 part-work can be completed by (A + B) in = (60/7) x (14/15) = 8 days.Correct Option: A
Work of A for 1 day = 1/15
Work of B for 1 day = 1/20
Work of (A + B) together for 1 day = 1/15 + 1/20 = (4 + 3)/60 = 7/60
Remaining work after A alone does for 1 day = 1 - 1/15 = 14/15
∵ 7/60 part-work can be complete by (A + B) in 1 days
∴ 14/15 part-work can be completed by (A + B) in = (60/7) x (14/15) = 8 days.