Time and Work
- Twenty-four men can complete a work in sixteen days. Thirty-two women can complete the same work in twenty-four days. Sixteen men and Sixteen women started working and worked for twelve days. How many more men are to be added to complete the remaining work in 2 days ?
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24 men complete the work in 16 days
⇒ Work that 16 men complete in 12 days = (16/24) x (12/ 16) = 1/2 part of work in 12 days.
32 women complete the work in 24 days
∴ Work that 16 women complete in 14 days = (16/32) x (14/24) = 7/24 part of work in (12 + 2) = 14 days.
So, the remaining part of the work which done by (sixteen men + sixteen women) and required additional no. of men in 2 days = 1 - (1/2 + 7/24) = 1/2 - 7/24 = 5/24 (part)Correct Option: B
24 men complete the work in 16 days
⇒ Work that 16 men complete in 12 days = (16/24) x (12/ 16) = 1/2 part of work in 12 days.
32 women complete the work in 24 days
∴ Work that 16 women complete in 14 days = (16/32) x (14/24) = 7/24 part of work in (12 + 2) = 14 days.
So, the remaining part of the work which done by (sixteen men + sixteen women) and required additional no. of men in 2 days = 1 - (1/2 + 7/24) = 1/2 - 7/24 = 5/24 (part)
Now, in 2 days 5/24 part part of the work is done by (24 x 16)/ 2 x (5/ 24) = 40 men
∴ Required additional no. of men = 40 - 16 =24.
- A and B can do a piece of work separately in 8 and 12 h. If they work alternate hours, A starting, when will the work be finished ?
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(A + B +)'s 2 h work = 1/8 + 1/12 = 5/24
(A + B)'s 8 h work = (5 x 8)/(24 x 2) = 5/6
Work done by A in 9th h = 1/8
Total work done upto 9th h = 5/6 + 1/8 = 23/24Correct Option: A
(A + B +)'s 2 h work = 1/8 + 1/12 = 5/24
(A + B)'s 8 h work = (5 x 8)/(24 x 2) = 5/6
Work done by A in 9th h = 1/8
Total work done upto 9th h = 5/6 + 1/8 = 23/24
Remaining wok = 1/24
B's 1 h work = 1/12
B can do 1/24 of the work = (1/24) x 12 = 1/2 h
So, both can finish the job in 91/2 h.
- In a garrison, there was food for 1000 soldiers for one month. After 10 days, 1000 more soldiers joined the garrison. How long would the soldiers be able to carry on with the remaining food ?
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Let us assume that each soldiers eats one unit of food per day. Thus, total units of food at the beginning will be 1000 x 30 = 30000. After 10 days the 100 soldiers would have eaten 1000 x 10 = 10000 units of food. Thus, food left after 10 days equals 20000 units. Now, there are a total of 2000 soldiers who eat one unit of food everyday.
Now, 30 x 1000 = 1000 x 10 + 2000 x D (here, D is number of days food will last)Correct Option: D
Let us assume that each soldiers eats one unit of food per day. Thus, total units of food at the beginning will be 1000 x 30 = 30000. After 10 days the 100 soldiers would have eaten 1000 x 10 = 10000 units of food. Thus, food left after 10 days equals 20000 units. Now, there are a total of 2000 soldiers who eat one unit of food everyday.
Now, 30 x 1000 = 1000 x 10 + 2000 x D (here, D is number of days food will last)
⇒ 30000 - 10000 = 2000 x D
∴ D = 20000/2000 = 10 days
- If 15 men can prepare 12 toys working 5 h per day in 16 days, then in how many days can 10 men prepare 15 toys working 8 h per day ?
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Using formula M1D1T1W1 = M2D2T2W2
M1 = 15, M2 = 10, D1 = 16, D2 = ?
T1 = 5, T2 = 8, W1 = 15, W2 = 12Correct Option: B
Using formula M1D1T1W1 = M2D2T2W2
M1 = 15, M2 = 10, D1 = 16, D2 = ?
T1 = 5, T2 = 8, W1 = 15, W2 = 12
Now, 15 x 16 x 5 x 15 = 10 x D2 x 8 x 12
D2 = (15 x 16 x 5 x 15)/(10 x 8 x 12)
= (15 x 15)/12 = 75/4 = 183/4 days
- A can do a piece of work in 10 days. B can do it in 24 days. If C also works with them then it take only 6 days to complete the whole work. In how many days C alone can complete the whole work?
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Efficiency of A = 100/10 = 10%
Efficiency of B = 100/24 = 4.16%
Efficiency of (A+B+C) = 100/6 = 16.66%
Efficiency of C = (16.66) - (10 + 4.16) = 2.5%Correct Option: B
Efficiency of A = 100/10 = 10%
Efficiency of B = 100/24 = 4.16%
Efficiency of (A+B+C) = 100/6 = 16.66%
Efficiency of C = (16.66) - (10 + 4.16) = 2.5%
Number of days required by C alone to finish the work = 100/2.5 = 40 days