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- Question
- A train running at 8/11 of its own speed reached a place in 5 1/ 2 h. How much time could be saved, if the train would have run as its own speed?
Options- A. 21/2 h
- B. 2 h
- C. 11/2 h
- D. 1 h
- Correct Answer
- 11/2 h
ExplanationNew speed = 8/11 of usual speed
New time = 11/8 of usual time
? 11/8 of usual time = 11/2 h
? Usual time = (11 x 8)/(2 x 11) = 4 h
? Time saved = 51/2- 4
= 11/2 - 1. A car during its journey travels 30 min at a speed of 40 km/h, another 45 min at a speed of 60 km/h and 2 h at a speed of 70 km/h. Find its average speed?
Options- A. 58 km/h
- B. 63 km/h
- C. 67 km/h
- D. 71 km / h Discuss
- 2. Walking 5/7 of his usual rate, a boy reaches his school 6 min late. Find his usual time to reach the school?
Options- A. 10 min
- B. 12 min
- C. 15 min
- D. 18 min Discuss
- 3. Two train leaves New Delhi at the same time. One travels towards North at 60 km/h and the other travels towards South at 40 km/h . After how many hours will the trains be 150 km apart?
Options- A. 3/2 h
- B. 4/3 h
- C. 3/4 h
- D. 15/2 h Discuss
- 4. Ram and Sita are walking towards each other with the speed of 8 km/h and 2 km/h, respectively over a road 160 km long. How soon will they meet?
Options- A. 16 h
- B. 8 h
- C. 10 h
- D. 20 h Discuss
- 5. A man walks 7.5 km at a speed of 3 km/h. At what speed would the man need two walk during the next 2 h to have an average of 4 km/h for the entire session?
Options- A. 3.65 km/h
- B. 4.75 km/h
- C. 5.25 km/h
- D. 6.50 km/h Discuss
- 6. Starting from his house, one day a student walks at a speed of 3 km/h and reaches his school 5 min late. Next day he increases his speed by 1 km/h and reaches the school 3 min early. How far is the school from his house?
Options- A. 1.6 km
- B. 1.24 km
- C. 1.36 km
- D. 1.8 km Discuss
- 7. A thief running at 8 km/h is chased by a policeman whose speed is 10 km/h. If the thief is 100 m ahead of the policeman, then the time required for the policeman to catch the thief will be
Options- A. 2 min
- B. 3 min
- C. 4 min
- D. 6 min Discuss
- 8. A person can row 7 1/ 2 km/h in still water. It takes him twice as long to row up a distance as to row down the same distance. Find the speed of the stream?
Options- A. 2 km/h
- B. 2.2 km/h
- C. 2.5 km/h
- D. 2.7 km/h Discuss
- 9. A streamer goes downstream from one port to another in 4 h. It covers the same distance upstream in 5 h. If the speed of the stream is 2 km/h , find the distance between the two ports?
Options- A. 50 km/h
- B. 60 km/h
- C. 70 km/h
- D. 80 km/h Discuss
- 10. The current of a stream runs at 1 km/h. A motorboat goes 35 km upstream and back again at the starting point in 12 h. What is the speed of motorboat in still water?
Options- A. 7 km/h
- B. 4 km/h
- C. 6 km/h
- D. 5 km/h Discuss
Time and Distance problems
Search Results
Correct Answer: 63 km/h
Explanation:
Average speed = [(30/60) x 40 + (45/60) x 60 + (2 x 70)] / [(30/60) + (45/60) + 2]
= (20 + 45 + 140)/[(30 + 45 + 120)/60]
= (205/195) x 60 km/h
= 63.07 km/h
= 63 km/h
Correct Answer: 15 min
Explanation:
Since, the boys now walks at 5/7 of usual speed, so he will take 7/5 of his usual time.
? Extra time = (7/5 - 1) x Usual time = 6 min (known)
? 2/5 x Usual time = 6
? Usual time = 15 min
Correct Answer: 3/2 h
Explanation:
Relative speed = 60 + 40 = 100 km/h
Time = Distance/speed = 150/ 00 = 3/2 h
Correct Answer: 16 h
Explanation:
Distance = 160 km
Relative Speed = 8 + 2 = 10
Time = Distance/Relative speed = 160/10 = 16 h
Correct Answer: 5.25 km/h
Explanation:
Let speed of walking be V km/h.
Total time taken = (7.5/3) + 2 = 4.5 h
Total distance covered = (7.5 + 2V) km
? (7.5 + 2V)/4.5 = 4
? 7.5 + 2V = 18
? 2V = 10.5
? V = 5.25
? Speed of walking = 5.25 km/h
Correct Answer: 1.6 km
Explanation:
Let the distance be D km
Difference in timings = 8 min = 8/60 h = 2/15 h
? D/3 - D/4 = 2/15
? D/12 = 2/15
? D = 2 x 12/15 = 1.6 km
Correct Answer: 3 min
Explanation:
Relative speed of policeman with thief = (10 - 8) = 2 km/h
Now, time taken to cover 100 m with speed of 2 km/h or 2000 m/h
Now, Speed = Distance / Time
? Time = D/S = 100/2000
= 1/20 h or 60/20 min = 3 min
Correct Answer: 2.5 km/h
Explanation:
Speed upstream + Speed downstream = 2 x 71/2 = 15 km/h
Since, the time taken is in the ratio 2 : 1
hence the speed will be in the ratio 1 : 2
? Speed upstream = (1/3) x 15 = 5 km/h
and speed downstream = (2/3) x 15 = 10 km/h
? Speed of stream = (10 - 5)/2 = 2.5 km/h
Correct Answer: 80 km/h
Explanation:
Let the distance between the two ports = L km
Then, speed downstream = L/4
and speed upstream = L/5
? Speed of the stream = 1/2(L/4 - L/5)
? 1/2[(5L - 4L)/20] = 2
? L = 80 km
Correct Answer: 6 km/h
Explanation:
Let the speed of boat in still water be V km/h. Then,
35/(V - 1) + 35/(V + 1) = 12
? 35(V + 1 + V - 1) = 12(V2 - 1)
? 6V2 - 35V - 6 = 0
? (V - 6)(6V + 1) = 0
? V = 6 (V = - 1/6 is not possible)
So, speed of boat in still water is 6 km/h.
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