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- Question
- A and B can do a piece of work in 72 days, B and C can do it in 120 days, A and C can do it in 90 days. In what time can A alone do it?
Options- A. 60 days
- B. 90 days
- C. 115 days
- D. 120 days
- Correct Answer
- 120 days
ExplanationCombined efficiency of A and B = 1/72 ....(i)
Combined efficiency of B and C = 1/120 ....(ii)
Combined efficiency of A and C = 1/90 ....(iii)
On adding Eqs. (i), (ii) and (iii), we get
2(A + B + C) = 1/72 + 1/120 + 1/90 = (5 + 3 + 4)/360
= 12 / 360 = 1 / 30
? A + B + C = 1/60 .....(iv)
i.e Combined efficiency is 1/60 or we can say together A, B and C can complete the work in 60 days.
On subtracting Eq. (ii)from Eq. (iv), we get
Efficiency of A = Combined efficiency of A, B and C - Combined efficiency of B and C
= 1/60 - 1/120 = 1/120
Hence, A alone can do it in 120 days - 1. A and B together can complete a piece of work in 35 days while A alone can complete the same work in 60 days. In how many days, B alone will be able to complete the same work?
Options- A. 80 days
- B. 84 days
- C. 88 days
- D. 92 days Discuss
- 2. Two friend A and B working together completed a work in 26 days. Their skills of doing the work are in the ratio 8 : 5. How many days will B take, if engaged alone?
Options- A. 673/5 days
- B. 421/4 days
- C. 563/5 days
- D. 642/3 days Discuss
- 3. A and B can do a piece of work in 12 days, B and C can do it in 15 days and C and A can do the same work in 20 days. Find the number of days in which A alone can do the same job?
Options- A. 20 days
- B. 30 days
- C. 45 days
- D. 60 days Discuss
- 4. A leak in the bottom of a tank can empty the full tank in 6 h. An inlet pipe fills water at the rate of 4 L in a min. When the tank is full, the inlet is opened and due to the leak the tank is empty in 8 h. Find the capacity of the tank?
Options- A. 5000 L
- B. 5670 L
- C. 5700 L
- D. 5760 L Discuss
- 5. A man, a women and a boy can do a job in 3, 4 and 12 days , respectively. How many boys must assist one man and one women to complete the job in one and a half days?
Options- A. 12
- B. 6
- C. 3
- D. 1 Discuss
- 6. Ram finishes a work in 7 days. Rahim finish the same job in 8 days and Robert in 6 days. They take turns to finish the work. Ram worked on the first day, Rahim on the second day and Robert on the third and then again Ram and so on. Who was working on the last day when work got finished?
Options- A. Ram
- B. Rahim
- C. Robert
- D. Rahim and Robert Discuss
- 7. 12 men and 16 boys can do a piece of work in 5 days while 13 men and 24 boys finish it in 4 days. 5 men and 10 boys will finish it in?
Options- A. 10 days
- B. 12 days
- C. 9 days
- D. 15 days Discuss
- 8. 'A' can do a piece of work in 2 hours, 'B' can do thrice the work in 8 hours and 'C' can do the same work as 'A' in 8 hours. If all of them work together, how long it would take them to complete the work?
Options- A. 1 hour
- B. 2 hour
- C. 3 hour
- D. 4 hours Discuss
- 9. If one man or two woman or three boys can finish a work in 88 days , then how many days will one man one woman and one boys together take to finish the same work?
Options- A. 46 boys
- B. 54 days
- C. 48 days
- D. 44 days Discuss
- 10. When A alone does a piece of work, he takes 25 days more than the time taken by (A + B) to complete that particular work, while B alone takes 49 days more than the time taken by (A + B) to finish the same work . A and B together will take what time for finish this work?
Options- A. 35 days
- B. 25 days
- C. 15 days
- D. 45 days Discuss
Time and Work problems
Search Results
Correct Answer: 84 days
Explanation:
In this question, A and B did the work for 35 days to complete it. A can complete the work in 60 days.
So, A did/A can + B did/B can = 1
? 35/60 + 35/x = 1
? x = 84 days
Correct Answer: 673/5 days
Explanation:
Skill ratio of A and B = 8 : 5
So, the time taken by A and B 5W and 8W, respectively.
According to the question, 1/8W + 1/5W = 1/26
? W = (13 x 26)/40
Now, time taken by B is 8W = 8 x 13 x 26/40
= 673/5 days.
Correct Answer: 30 days
Explanation:
Work done by A and B in one day = 1/12
Work done by B and C in one day = 1/15
Work done by C and A is one day = 1/20
On adding all these,
2(A + B + C)'s work of one day = 1/12 + 1/15 +1/20 = 1/5
? (A + B + C)'s one day work = 1/10
? A' s one day work = (A + B + C)'s one day work - (B + C )'s one day work
? A's one day work 1/10 - 1/15 = 1/30
Hence, A can do this work in 30 days.
Correct Answer: 5760 L
Explanation:
Efficiency of the leak = 1/6
Combined efficiency of leak and inlet pipe
So, efficiency of inlet pipe = 1/6 - 1/8 = (4 - 3)/24 = 1/24
Inlet pipe can fill the tank in 24 h, at rate of 4 L/min.
? Capacity = 24 x 60 x 4 = 5760 L
Correct Answer: 1
Explanation:
Portion of work completed by one man in 11/2 days.
i.e., 3/2 days = 3/(2 x 3) = 1/2
Portion of work completed by one women in 11/2 days.
i.e., 3/2 days = 3/(2 x 4) = 3/8
? Portion of work completed by boys = 1 - (1/2 + 3/8) = 1/8
Now, portion of work completed by each boy in 3/2 days = 3/(2 x 12) = 1/8
Hence, only one boys would be required.
Correct Answer: Ram
Explanation:
Three day work or Ram, Rahim and Robert = 1/7 + 1/8 + 1/6
= (24 + 21 + 28)/168 = 73/168
Their six days work = (2 x 73)/168 = 146/168 = 73/84
Now, its Ram's turn to work on seventh day.
? 73/84 + 1/7 = 73 + 12/84 = 85/84 > 1
So, Ram will finish the work before the end of day.
Hence, Ram is working for the last day.
Correct Answer: 10 days
Explanation:
(12 men + 16 boys) can do a work in 5 days.
(60 men + 80 boys) can do a work in 1 day.
(13 men + 24 boys) can do a work in 4 days.
(52 men + 96 boys) can do a work in 1 day.
? 60 men + 80 boys = 52 men + 96 boys
8 men = 16 boys and 1 man = 2 boys
Now, 12 men + 16 boys = (12 x 2 + 16) boys
= 40 boys can do the work in 5 days
? 5 men + 10 boys = [5 x 2 + 10] boys
= 20 boys will take
= (40 x 5)/20 = 10 days
Correct Answer: 1 hour
Explanation:
Efficiency of A = 50% [100/2]
Efficiency of B = 37.5% [100/(8/3)]
Efficiency of C = 12.5% [100/8]
Combined efficiency of A,B and C = 100%
So, they complete the work in 1 hour.
Correct Answer: 48 days
Explanation:
1 man = 2 woman = 3 boys
? 1 man + 1 woman + 1 boy = (3 + 3/2 + 1) boys = 11/2 boys
Here M1 = 3 M2 = 11/2, D1 = 88 and D2 = ?
According to the formula
M1D1 = M2D2
? D2 = M1D1/M2
? Required number of days
= 3 x 2 x 88/11 = 3 x 2 x 8 = 48 days
Correct Answer: 35 days
Explanation:
According to the formula,
Required time = ?ab
Where a = 25 and b = 49
? Require time = ?25 x 49 = 5 x 7
= 35 days
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