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- Question
- A and B can do a piece of work in 12 days. B and C in 15 days. C and A in 20 days. A alone can do the work in?
Options- A. 152/3
- B. 24 days
- C. 30 days
- D. 4 days
- Correct Answer
- 30 days
Explanation? [(A + B) + (B + C) + (C + A)]'s 1 day's work = (1/12 + 1/15 + 1/20) = 1/5
? 2(A + B + C)'s 1 days work = 1/5
? (A + B + C)'s 1 day's work = 1/10
&rArr A's 1 day's work = (1/10 - 1/15) = 1/30
? A alone can finish it in 30 days. - 1. A and B can do a piece of work in 18 days, B and C in 24 days, A and C in 36 days. In what time can they do it all working together?
Options- A. 12 days
- B. 13 days
- C. 16 days
- D. 26 days Discuss
- 2. A and B can do a piece of work in 6 days and A alone can do it in 9 days. The time taken by B alone to do the same work is?
Options- A. 18 days
- B. 15 days
- C. 12 days
- D. 71/2 Discuss
- 3. A and B can together do a piece of work in 15 days. B alone can do it 20 days. In how many days can A alone do it?
Options- A. 30 days
- B. 40 days
- C. 45 days
- D. 60 days Discuss
- 4. 20 persons completed 1/3rd of the work in 12 days. How many more person are required to finish the rest work in next 12 days?
Options- A. 20
- B. 12
- C. 18
- D. 40 Discuss
- 5. A contractor undertook a work to complete in 60 days. But just after 20 days he observed that only 1/5th of the project work had been completed. To complete the work in time (i.e,In rest days) minimum how many workers he had to increase, if there were initially 75 workers were deployed for the task?
Options- A. 25
- B. 50
- C. 75
- D. can't be determined Discuss
- 6. A can do a piece of work in 30 days while B can do it in 40 days. In how many days can A and B working together do it?
Options- A. 70 days
- B. 423/4 days
- C. 271/7 days
- D. 171/7 days Discuss
- 7. A can do (1/3) of a work in 5 days and B can do (2/5) of the work in 10 days. In how many days both A and B together can do the work?
Options- A. 73/4
- B. 84/5
- C. 93/8
- D. 10 Discuss
- 8. A can do a piece of work in 20 days which B can do in 12 days. B worked at it for 9 days. A can finish the remaining work in?
Options- A. 3 days
- B. 5 days
- C. 7 days
- D. 11 days Discuss
- 9. A and B together can do a work in 8 days. If A alone can do it in 12 days, then in how many days can B alone do it?
Options- A. 12 days
- B. 20 days
- C. 24 days
- D. 28 days Discuss
- 10. Rohan and Sunil separately can complete a work in 8 hours and 4 hours respectively. How much time will they take when working together?
Options- A. 22/3
- B. 11/3
- C. 3 hours
- D. 2 hours Discuss
Time and Work problems
Search Results
Correct Answer: 16 days
Explanation:
(A + B)'s 1 day's work = 1/18
(B + C)'s 1 day's work = 1/24
(A + C)'s 1 day's work = 1/36
Adding 2 (A + B + C)'s 1 day's work = (1/18 + 1/24 + 1/36) = 1/8
? (A + B + C)'s day's work = 1/16
Hence, all working together can finish it in 16 days.
Correct Answer: 18 days
Explanation:
B's one day's work = (1/6 - 1/9) = 1/18
? B alone can finish it in 18 days.
Correct Answer: 60 days
Explanation:
A's 1 day's work = (1/15 - 1/20) = 1/60
? A alone can finish it in 60 days.
Correct Answer: 20
Explanation:
Work done = 1/3
Remaining work = 2/3
So for double work in same days we need double number of people i.e. 40.
So, 20 men will be increased.
Correct Answer: 75
Explanation:
Work done = 1/5
remaining work = 4/5
? 4 (20 x 75) = 40 x N
N = 150
Therefore 75 men should be increased.
Correct Answer: 171/7 days
Explanation:
(A + B)'s 1 day's work = (1/30 + 1/40) = 7/120
? Time taken by both to finish the work = 120/7days = 171/7 days
Correct Answer: 93/8
Explanation:
? 1/3 of work is done by A in 5 days.
? Whole work will be done by A in 15 days.
? 2/3 of work is done by B in 10 days.
Whole work will be done by B in 10 x (5/2) i.e., 25days
? (A + B)'s 1 day's work = (1/15 + 1/25) = 8/75
So, both together can finish it in 75/8 days, i.e., 93/8days.
Correct Answer: 5 days
Explanation:
B's 9 day's work = 9 x (1/12) = 3/4
Remaining work = (1 - 3/4) = 1/4
1/4 work is done by A in = 20 x (1/4) = 5 days.
Correct Answer: 24 days
Explanation:
Required time taken by B to complete the work = xy / x - y
[Here x = 12 and y = 8]
? required time = (12 x 8) / (12 - 8) = 96/4 = 24 days
Correct Answer: 22/3
Explanation:
Required time taken to complete the work by both together = x y / x + y
(Here x = 8 and y = 4)
? Required time = (8 x 4)/(8 + 4) = 32/12 = 22/3 hours
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