Time & Work – Section1

Question #1: A completes a work in 12 days and B complete the same work in 24 days. If both of them work together, then the number of days required to complete the work will be:
A) 7 days
B) 8 days
C) 9 days
D) 10 days

Option 'B' : 8 days
Hint:
If A can complete a work in x days and B can complete the same work in y days, then, both of them together can complete the work in x y/ x+ y days
Therefore, here, the required number of days = 12 × 24/ 36 = 8 days.

Question #2: If 3 persons can do 3 times of a particular work in 3 days, then, 7 persons can do 7 times of that work in :
A) 3 days
B) 4 days
C) 5 days
D) 6 days

Option 'A' : 3 days
Hint:
That is, 1 person can do one time of the work in 3 days.
Therefore, 7 persons can do 7 times work in the same 3 days itself.

Question #3: 12 men work 8 hours per day to complete the work in 10 days. To complete the same work in 8 days, working 15 hours a day, the number of men required is :
A) 7 days
B) 8 days
C) 9 days
D) 6 days

Option 'B' : 8 days
Hint:
That is, 1 work done = 12 × 8 × 10
Then, 12 8 × 10 = No. of men required × 15 × 8
No. of men required = 12 × 8 × 10/15× 10 = 8 days.

Question #4: 30 laborers working 7 hours a day can finish a piece of work in 18 days. If the laborers work 6 hours a day, then the number of laborers required to finish the same piece of work in 30 days will be :
A) 19 days
B) 20 days
C) 21 days
D) 22 days

Option 'C' : 21 days
Hint:
1 work done = 30 × 7 ×18 = No. of laborers × 6 × 30
No. of laborers = 30 × 7 × 18/6 × 30 = 21

Question #5: A and B together can plough a field in 10 hours but by himself A requires 15 hours. How long would B take to plough the same field?
A) 20 hours
B) 30 hours
C) 40 hours
D) 50 hours

Option 'B' : 30 hours
Hint:
If A and B together can do a piece of work in x days and A alone can do the same work in y days, then B alone can do the same work in x y/ y – x days.
Therefore, the No. of hours required by B = 10 × 15/ 15 – 10 = 150/5 = 30 hours.

Question #6: A can do a piece of work in 5 days and B can do the same work in 10 days. How many days will both take to complete the work?
A) 1 1/3 days
B) 4 1/3 days
C) 2 1/3 days
D) 3 1/3 days

Option 'D' : 3 1/3 days
Hint:
If A can complete a work in x days and B can complete the same work in y days, then, both of them together can complete the work in x y/ x+ y days.
That is, the required No. of days = 5 × 10/15 = 3 1/3 days.

Question #7: A group of workers accepted to do a piece of work in 25 days. If 6 of them did not turn for the work and the remaining workers did the work in 40 days, then the original number of workers was :
A) 14
B) 15
C) 16
D) 17

Option 'C' : 16
Hint:
Let the original number of workers be ‘x’
Then, x × 25 = (x – 6) × 40
25x = 40x -240
240 = 40x -25x = 15x
x = 240/15 = 16.

Question #8: If 8 men can dig a well in 18 days, then the number of days, 12 men will take to dig the same well will be :
A) 12 days
B) 13 days
C) 14 days
D) 15 days

Option 'A' : 12 days
Hint:
Work done = 8 × 18
Then, 8 × 18 = 12 × No. of days
No. of days = 8 × 18/12 = 12 days

Question #9: A certain number of men can do a work in 40days. If there were 8 men more, it could be finished in 10 days less. How many men were there initially?
A) 23
B) 24
C) 25
D) 26

Option 'B' : 24
Hint:
Let ‘x’ be the initial number of men
Then, 1 work done = x × 40
Then, x × 40 = (x + 8) (40 – 10)
40x = 30x + 240
10x = 240
Therefore, x = 240/10 = 24 men.

Question #10: A works twice as fast as B. if B can complete a work in 12 days independently. The number of days in which A and B can together finish the work?
A) 5 days
B) 6 days
C) 4 days
D) 3 days

Option 'C' : 4 days
Hint:
If B takes 12 days to finish the work, then A takes 6 days to finish the same work.
If A can complete a work in x days and B can complete the same work in y days, then, both of them together can complete the work in x y/ x+ y days.
Therefore, the Number of days taken by A and B together to finish the same work = 6 × 12/18 = 4 days.

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