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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 and do it in 90 days. In what time can A alone do it?
Options- A. 80 days
- B. 100 days
- C. 120 days
- D. 150 days
- Correct Answer
- 120 days
Explanation(A + B )'s 1 day ' s work = 1/72
(B + c)'s 1 day' s work = 1/120
(A + C)'s 1 day's work = 1/90
2(A + B + C)'s 1 days work = 1/72 + 1/120 + 1/90
? ( A + B + C )'s 1 day's work (5 + 3 + 4)/(360 x 2) = 12/(360 x 2) = 1/60
? A's 1 day's work = (A + B + C) 's 1 day's work - (B + C)'s 1 day's work
= 1/60 - 1/120 = (2 - 1)/120 = 1/120
? A alone can finish the work in 120 days. - 1. A and B can do a piece of work in 18 days. B and C in 24 days, C and A in 36 days. Find the time in which A, B and C working together can finish the work.
Options- A. 8
- B. 16
- C. 24
- D. 36 Discuss
- 2. If 3 men or 4 women can built a wall in 43 days, in how many days can 7 men and 5 women build this wall?
Options- A. 16 days
- B. 25 days
- C. 21 days
- D. 12 days Discuss
- 3. 45 people take 18 days to dig a pond. If the pond would have to be dug in 15 days, then the number of people to the employed will be?
Options- A. 50
- B. 54
- C. 60
- D. 72 Discuss
- 4. 20 men complete one-third of a work in 20 days. How many more men should be employed to finished the rest of work in 25 more days.?
Options- A. 15
- B. 12
- C. 18
- D. 25 Discuss
- 5. If m men working m h per day, can do m units of work in m days, then n men working n h per day would be able to complete how units of work in days?
Options- A. n3/m2
- B. m3/n2
- C. m4/n2
- D. n4/m3 Discuss
- 6. 25 men reap a field in 20 days. When should 15 men leave the work, if the whole field is to be reaped in 37 1/ 2 day after they leave the work?
Options- A. 6 days
- B. 4 days
- C. 5 days
- D. None of these Discuss
- 7. A can do a piece of work in 5 hours, B in 9 hours and C in 15 hours. If C could work with them for 1 hour only the time taken by A and B together to complete the work is?
Options- A. 2 hours
- B. 3 hours
- C. 31/2
- D. 4 hours Discuss
- 8. A can do a piece of work in 24 days while B alone can do it in 16 days. But with the help of C, they finish the work in 8 days. C alone can do the work in?
Options- A. 32 days
- B. 36 days
- C. 40 days
- D. 48 days Discuss
- 9. A can do a certain job in 10 days. B is 60% more efficient than A. The number of days, it takes B to do the same piece of work is?
Options- A. 6
- B. 61/4
- C. 62/3
- D. 8 Discuss
- 10. A, B and C together earn Rs. 150 per day while A and C together earn Rs. 94 and B and C together earn Rs. 76. The daily earning of C is?
Options- A. Rs. 75
- B. Rs. 56
- C. Rs. 34
- D. Rs. 20 Discuss
Time and Work problems
Search Results
Correct Answer: 16
Explanation:
(A+ B )' s 1 day ' s work = 1/18
(B +C )'s 1 day ' s work = 1/24
(C + A) 's 1 day 's work = 1/36
From Eqs. (i), (ii) and (iii), we get
2(A + B + C)' s 1 day 's work = 1/18 + 1/24 + 1/36
(A + B + C)'s 1 day's work = (4 + 3 + 2)/(72 x 2)
= 9/(72 x 2) = 1/16
? (A + B + C) can complete the work in 16 days
Correct Answer: 12 days
Explanation:
3 men = 4 women
? 1 man = 4/3 women
? 7 men + 5 women = 7 x (4/3) + 5 = 43/3 women
? M1D1W2 = M2D2W1
? 4 x 43 x 1 = (43/3) x D2 x 1
? D2 = 3 x 4 = 12 days
Correct Answer: 54
Explanation:
Given, M1 = 45, D1 = 18, M2 = ? , D2 = 15
By using the formula,
M1D1 = M2D2
? M2 = M1D1/D2
? M2 = (45 x 18)/15 = 3 x 18
? M2 = 54
Correct Answer: 12
Explanation:
Given, M1 = 20.
M2 = 20 + k
W1 = 1/3, W2 = 1 - 1/3 = 2/3
D1 = 20 and D2 = 25
According to the formula,
M1D1W2 = M2D2W1
? 20 x 20 x (2/3) = (20 + k) x 25 x 1/3
? 20 x 20 x (2/3) = (20 + k) x 25/3
? 16 x 2 = 20 + k
? k = 32 - 20 = 12
Correct Answer: n3/m2
Explanation:
Let the required number of units of work = k
According to the formula,
W1= m and W2 = k
M1T1D1W2 = M2T2D2W1
? m x m x m x k = n x n x n x m
? x= (m x n3) / m3 = n3/m2
Correct Answer: 5 days
Explanation:
25 men reap the field in 20 days
? 10 men can reap the feild in (20 x 25)/ 10 = 50 days.
When 15 men leave the work, 10 men remain and they can reap in 371/2 days
= (371/2)/ 50 = 3/4 of the field
Hence, all men must work till (1 - 3/4) = 1/4 of the field is reaped in 20/4 = 5 days.
Correct Answer: 2 hours
Explanation:
? (1/5 + 1/9 + 1/15) = 17/45 work is finished in 1 hour
? Remaining work = 1 - 17/45 = 28/45
? (A + B)'s 1 hour's work = 1/5 + 1/9 = 14/45
14/45 work is done by (A and B) in 1 hour
28/45 work will be done by A and B in (45/14) x (28/45) = 2 hours
Correct Answer: 48 days
Explanation:
? C's 1 day's work
= [( A + B + C)'s 1 day's work] - [(A + B)'s 1 day's work]
= [1/8 - (1/24 + 1/16)] = (1/8 - 5/48) = 1/48
? C alone can do it in 48 days.
Correct Answer: 62/3
Explanation:
1 day work of A = 1/10 = 0.1
1 day work of B = 1/10 + 60% of 1/10 = 0.1 + 0.06 = 0.16
So number of days taken by B to complete the work = 1/0.16
= 62/3
Correct Answer: Rs. 20
Explanation:
? B's daily earning = Rs. (150 - 94) = Rs. 56
? A's daily earning = Rs. (150 - 76) = Rs. 74
? C's daily earning = Rs. [(150 - (56 + 74)] = Rs. 20
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