Time and Work
- A and B can complete a job in the 24 days working together. A alone can complete it in 32 days. Both of them worked together for 8 days and then A left. The number of days B will take to complete the remaining job is
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Let B will take N days to complete the remaining job.
According to the question
(1/A) + (1/B) = 1/24 and 1/A = 1/32
∴ 1/B = (1/24) - (1/32) = 1/96
⇒ B = 96 days
According to the question,
8[(1/A) + (1/B)] + N x (1/B) = 1Correct Option: C
Let B will take N days to complete the remaining job.
According to the question
(1/A) + (1/B) = 1/24 and 1/A = 1/32
∴ 1/B = (1/24) - (1/32) = 1/96
⇒ B = 96 days
According to the question,
8[(1/A) + (1/B)] + N x (1/B) = 1
⇒ 8 x (1/24) + (N/96) = 1
⇒ (1/3) + (N/96) = 1
⇒ N/96 = 1 -1/3
∴ N = (2 x 96)/3 = 64
Hence, B complete the remaining job in 64 days
- 90 men are engaged to do piece of work in 40 days but it is found that in 25 days, 2/3 work is complete. How many men should be allowed to go off, so that the work finished in time ?
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Let N men are allowed to go off,
M1= 90, D1 = 25, D2 = 15
W1 = 2/3, W2 = 1 - (2/3) = 1/3
M2 = 90 - N
According to the formula, M1D1W2 = M2D2W1
⇒ (90 x 25) (1/3) = (90 - N) x 15 x (2/3)Correct Option: B
Let N men are allowed to go off,
M1= 90, D1 = 25, D2 = 15
W1 = 2/3, W2 = 1 - (2/3) = 1/3
M2 = 90 - N
According to the formula, M1D1W2 = M2D2W1
⇒ (90 x 25) (1/3) = (90 - N) x 15 x (2/3)
⇒ 90 x 25 x (1/3) = 10(90 - N)
⇒ 75 = 90 - N
∴ N = 90 - 75 = 15
- 20 workers working for 5 h per day complete a work in 10 days. If 25 workers are employed to work 10 h per days, what is the time required to complete the work ?
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Given, M1= 20, M2 = 25, T1 = 5, T2 = 10, D1 = 10 and D2 = ?
According to the formula,
M1T1D1= M2T2D2Correct Option: A
Given, M1= 20, M2 = 25, T1 = 5, T2 = 10, D1 = 10 and D2 = ?
According to the formula,
M1T1D1= M2T2D2
⇒ 20 x 5 x 10 = 25 x 10 x D2
∴ D2 = 20 x 5 x 10/25 x 10 = 4 days
- A, Band C can do a piece of work individually in 8, 12 and 15 days, respectively. A and B start working but A quits after working for 2 days. After this, C joins B till the completion of work. In how many days will the work be completed ?
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Work done by A and B in 1 day
= (1/8) + (1/12) = 5/24
2 day's work of A and B = 10/24
After 2 day's A left the work
∴ Remaining work = 1 - (10/24) = 14/24
One day work of B and C together = (1/12) + (1/15) = 9/60
So, the number of days required by B and C to finish work
= (14/24) / (9/60) = (14/24) x (60/9) = 35/9Correct Option: A
Work done by A and B in 1 day
= (1/8) + (1/12) = 5/24
2 day's work of A and B = 10/24
After 2 day's A left the work
∴ Remaining work = 1 - (10/24) = 14/24
One day work of B and C together = (1/12) + (1/15) = 9/60
So, the number of days required by B and C to finish work
= (14/24) / (9/60) = (14/24) x (60/9) = 35/9
∴ Total days to complete the work = 2 + (35/9) = 53/9 = 58/9 days
- A and B together can complete a work in 3 days. They started together but after 2 days, B left the work. If the work is completed after 2 more days, B alone could do the work in how many days ?
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(A + B)'s 2 day's work = 2 x (1/3) = 2/3
Remaining work = 1 - (2/3) = 1/3
A will complete 1/3 work in 2
A will complete 1 work in 6Correct Option: B
(A + B)'s 2 day's work = 2 x (1/3) = 2/3
Remaining work = 1 - (2/3) = 1/3
A will complete 1/3 work in 2
A will complete 1 work in 6
A's 1 days work = 1/6
B's 1 day's work = (1/3) - (1/6) = 1/6
∴ B will take 6 days to complete the work alone.