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- Question
- 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
- Correct Answer
- 22/3
ExplanationRequired 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 - 1. 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
- 2. 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
- 3. 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
- 4. 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
- 5. 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 Discuss
- 6. A can do a piece of work in 12 days. B is 60% more efficient than A. The number of days, it take B to do the same piece of work is?
Options- A. 71/2
- B. 61/4
- C. 8
- D. 6 Discuss
- 7. A can finish a piece of work in 12 days while B can do it in 15 days. If both work at it together, what time will they take to do the work?
Options- A. 6 days
- B. 8 days
- C. 62/3 days
- D. 101/15 days Discuss
- 8. A can do a piece of work in 14 days while B can do it in 21 days. In how many days, working together they will complete the whole work?
Options- A. 10.5
- B. 8
- C. 8.4
- D. 9 Discuss
- 9. A can do a piece of work in 24 days. If B is 60% more efficient than A, then the number of days required by B to do the same piece of work is?
Options- A. 10
- B. 15
- C. 12
- D. 9.6 Discuss
- 10. A is twice as good a workman as B and together they finish a piece of work in 14 days. In how many days can a alone finish the work?
Options- A. 18
- B. 20
- C. 21
- D. 24 Discuss
Time and Work problems
Search Results
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: 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: 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: 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: 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.
Correct Answer: 71/2
Explanation:
A's 1 day's work = 1/12
B's 1 day's work = 1/12 + 60% of 1/12 = 1/12 x 160/100 = 2/15
? B can do the work in 15/2 days = 71/2 days.
Correct Answer: 62/3 days
Explanation:
Efficiency of A = 100/12 = 8.33%
Efficiency of B = 100/15 = 6.66%
Combined efficiency of A and B = 8.33 + 6.66 = 15%
Number of days taken by A and B, when worked together = 100/15
= 62/3 days
Correct Answer: 8.4
Explanation:
One day's work of A and B = 1/14 + 1/21 = 5/42
? Required number of days = 42/5 = 8.4 days
Correct Answer: 15
Explanation:
Efficiency of A = 4.16%
Efficiency of B = 1.6 x 4.16 = 6.66%
? Number of days required by B = 100/6.66 = 15 days
Correct Answer: 21
Explanation:
One day's work of A and B = 1/x + 1/2x = 1/14
? x = 21
Since A is twice efficient as B so A will take half of the day taken by B.
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