Time and Work problems
- 1. A man, on tour travel first 160 km, at 64 km/hr. and the next 160km at 80km/hr. the average speed for the first 320 km. of the tour is?
Options- A. 35.55km/hr.
- B. 71.11km/hr.
- C. 36km/hr.
- D. 72km/hr. Discuss
Correct Answer: 71.11km/hr.
Explanation:
Average speed = 2t1 x t2/( t1 + t2)
= (2x64x80)/(64+80)km
= (2 x 64 x 80 ) / 144 km/hr.
=71.11km/hr.
- 2. By walking at 3/4 of his usual speed, a man reaches his office 20 minute later than usual. this usual time is?
Options- A. 30 minute
- B. 60 minute
- C. 75 minute
- D. 1 hour 30 minute Discuss
Correct Answer: 60 minute
Explanation:
At a speed of 3/4 of the usual speed, the time taken is 4/3 of the usual time
= (4/3 of usual time ) ? (usual time ) = 20min.
? 4x/3 -x = 20
? x/3 =20
? x=60 min
- 3. A man travels 35 km partly at 4 km/hr and at 5 km/hr. If he covers former distance at 5 km/hr and later distance at 4 km/hr, he could cover 2 km more in the same time. The time taken to cover the whole distance at original rate is
Options- A. 9 hours
- B. 7 hours
- C. 4.5 hours
- D. 8 hours Discuss
Correct Answer: 8 hours
Explanation:
Suppose the man covers first distance in x hrs. and second distance in y hrs.
Then , 4x + 5y = 35 and 5x +4y= 37
Solving these equation , we get
X=5 and y=3
Total time taken = (5+3) hrs= 8hrs
- 4. 6 men or 10 women can reap a field in 15 days, then the number of days that 12 men and 5 women will take to reap the same field is :
Options- A. 5
- B. 6
- C. 8
- D. 12 Discuss
Correct Answer: 6
Explanation:
Work done by 6 men = work done by 10 women.
Work done by 1 man = work done by 10 / 6 = 5/3 women
? 12 men + 5 women = 12 x ( 5 / 3) + 5 = 25 women
? W1 x D 1 = W2 x D2 W = women, D=days
10 X 15 = 25 x D2
D2 = 6
- 5. 6 children and 2 men complete a certain piece of work in 6 days. Each child takes twice the time taken by a man to finish the work. In how many days will 5 men finish the same work?
Options- A. 6
- B. 8
- C. 9
- D. 15 Discuss
Correct Answer: 6
Explanation:
6C + 2M = 6days
36C + 12M = 1 days
Again 1M = 2C
? 36+12X2 = 1 day
60 children can do the work in 1 day
Now, 5 men = 10 children
? 10 children can do the work in 6 days.
- 6. 2 men or 5 women or 7 boys can finish a work in 469 days, then the number of days taken by 7 men, 5 women and 2 boys to finish the work is :
Options- A. 134
- B. 106
- C. 100
- D. 98 Discuss
Correct Answer: 98
Explanation:
2 men = 7 boys
? 1 man = 7/2 days
5 women = 7 boys
? 1 women = 7/5 boys
7 men + 5 women + 2 boys = 7 x 7/2 + 5 x 7/5 + 2 = 67/2 boys
Now, B1 x D1 = B2 x D2
7 X 469 = 67/2 x D2
D2 = 98 days
- 7. 314 weavers weaves 6594 shawls in 1/6 hours. What is the number of shawls weaved per hour by an average weaver?
Options- A. 42
- B. 21
- C. 102
- D. 126 Discuss
Correct Answer: 126
Explanation:
In 1 hour 314 weavers weave = 6594 x 6 shawls
In 1 hour 1 weaver weaves = ( 6594 x 6 ) / 314 shawls = 126 shawls
- 8. The Ratio of efficiencies of A, B and C is 6 : 5 : 4 and if A, B and C received total Rs. 27000 for the whole work. What is the share of C, if the money is distributed in the ratio of amount of work done, individually?
Options- A. 2700
- B. 7200
- C. 14400
- D. 6300 Discuss
Correct Answer: 7200
Explanation:
Ratio of efficiencies of A,B and C = 6 : 5 : 4
? Share of C = [4/(6+5+4)] x 27000 = 7200
- 9. If 2 men or 3 women or 4 boys can do a piece of work in 52 days. Then the same piece of work will be done by 1 man, 1 woman and 1 boy in?
Options- A. 48 days
- B. 36 days
- C. 45 days
- D. none of these Discuss
Correct Answer: 48 days
Explanation:
Work done by 2 men = 3 woman = 4 boys
? 1 man = 2 boys
1 woman = 4/3 boys
? boys X days = 4 X 52 (boys - days)
Again 1 man + 1 woman + 1 boy = 2 + 4/3 + 1 = 13/3 boys
B1 x D1 = B2 x D2 B = boys, D = days
4 X 52 = 13/3 x D2
D2 = 48 days
- 10. 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
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.
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