Time and Work
- x can copy 80 pages in 20 hours, x and y together can copy 135 pages in 27 hours. Then y can copy 20 pages in
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According to question ,
Number of pages copied by x in hour = 80 = 4 20 Number of pages copied by x and y in 1 hour = 135 = 5 27
Correct Option: A
According to question ,
Number of pages copied by x in hour = 80 = 4 20 Number of pages copied by x and y in 1 hour = 135 = 5 27
∴ Number of pages copied by y in 1 hour = 5 – 4 = 1
∴ Required time = 20 hours.
- X can do a work in 16 days. In how many days will the work be completed by Y, if the efficiency of Y is 60% more than that of X ?
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Ratio of time taken by X
and Y = 160 : 100 = 16 : 1
Suppose Y takes y days to the work.
Then, 1.6 : 1 = 16 : yCorrect Option: A
Ratio of time taken by X
and Y = 160 : 100 = 16 : 1
Suppose Y takes y days to the work.
Then, 1.6 : 1 = 16 : y
∴ y = (16 x 1)/1.6 = 10 days
- A does 20 % less work then B. If A can complete a piece of work in
71/2h, then B can do it in
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Efficiency ∝ 1/Time taken
Correct Option: B
Let time taken by B = N
Efficiency ∝ 1/Time taken
So, if B is 100% efficient, then A is 80% efficient.
So, 80/100 = N /(15/2)
∴ N = 6 h
- A alone can do a certain job in 15 days, while B alone can do it in 10 days. A started the work and was joined by B after 5 days. The work lasted for how many days ?
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A's 5 days' work = (1/15) x 5 = 1/3
Remaining work = 1 - (1/3) = 2/3
∴ (A + B)'s 1 day's work
= (1/15) + (1/10)Correct Option: D
A's 5 days' work = (1/15) x 5 = 1/3
Remaining work = 1 - (1/3) = 2/3
∴ (A + B)'s 1 day's work
= (1/15) + (1/10)
= (2 + 3(/30
= 5/30
= 1/6
∴ 2/3 work will be finished by (A + B) in (2/3) x 6 days or in 4 days .
∴ Total time taken = (5 + 4) days = 9 days
- P can do piece of work in 12 days, while Q alone can finish it in 8 days. With the help of R, they can finish the work in 4 days. How long will R take to finish the work alone ?
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P,s 1 day's work = 1/12
Q's 1 day's work = 1/8
(P + Q)'s 1 day's work = (1/12) + (1/8)
= (2 + 3)/24
= 5/24
(P + Q + R)'s 1 day's work = 1/4
∴ R's 1 day's work = (1/4) - (5/24) = (6 - 5)/24 = 1/24Correct Option: D
P,s 1 day's work = 1/12
Q's 1 day's work = 1/8
(P + Q)'s 1 day's work = (1/12) + (1/8)
= (2 + 3)/24
= 5/24
(P + Q + R)'s 1 day's work = 1/4
∴ R's 1 day's work = (1/4) - (5/24) = (6 - 5)/24 = 1/24
∴ R will finish the work alone in 24 days.
∴ Required time = 24 days
