11) A man in a train notices that he can count 41 telephone posts in one minute. If they are known to be 50 metres apart, then at what speed is the train travelli
- 1) 60 km/hr
- 2) 100 km/hr
- 3) 110 km/hr
- 4) 120 km/hr
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Ans. D
Explanation :
Number of gaps between 41 poles = 40
So total distance between 41 poles = 40*50
= 2000 meter = 2 km
In 1 minute train is moving 2 km/minute.
Speed in hour = 2*60 = 120 km/hour
12) A train traveled at an average speed of 100 km/hr, stopping for 3 minutes after every 75 km. How long did it take to reach its destination 600 km from the starting poin
- 1) 6 hours 24 mins
- 2) 6 hours 21 mins
- 3) 6 hours 18 mins
- 4) 6 hours 15 mins
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Ans. B
Explanation :
Time taken to cover 600 km = 6 hours [because train speed is 100 km/hr]
Number of stops =
begin{aligned}
frac{600}{75} - 1 = 7 text{Total time on stops =}7*3 = 21 mins
end{aligned}
Total time taken by train = 6 hours 21 mins
13) A person travels equal distances with speed of 3 km/hr, 4 km/hr and 5 km/hr and takes a total of 47 minutes. Find the total dist
- 1) 3 km
- 2) 4 km
- 3) 6 km
- 4) 9 km
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Ans. A
Explanation :
Let the distance be 3x km,
then,
\begin{aligned}
\frac{x}{3} +\frac{x}{4} +\frac{x}{5} = \frac{47}{60} \\frac{47x}{60} =\frac{47}{60} \x = 1
\end{aligned}
So total distance = 3*1 = 3 Km
14) A walks around a circular field at the rate of one round per hour while B runs around it at the rate of six rounds per hour. They start at same point at 7:30 am. They shall first cross each other a
- 1) 7:15 am
- 2) 7:30 am
- 3) 7: 42 am
- 4) 7:50 am
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Ans. C
Explanation :
Relative speed between two = 6-1 = 5 round per hour
They will cross when one round will complete with relative speed,
which is 1/5 hour = 12 mins.
So 7:30 + 12 mins = 7:42
15) Two boys starting from the same place walk at a rate of 5kmph and 5.5kmph respectively. What time will they take to be 8.5km apart, if they walk in the same directio
- 1) 15 hours
- 2) 16 hours
- 3) 17 hours
- 4) 18 hours
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Ans. C
Explanation :
In this type of questions we need to get the relative speed between them,
The relative speed of the boys = 5.5kmph â€“ 5kmph
= 0.5 kmph
Distance between them is 8.5 km
Time = Distance/Speed
Time= 8.5km / 0.5 kmph = 17 hrs
16) Excluding stoppages, the speed of a bus is 54 kmph and including stoppages, it is 45 kmph. For how many minutes does the bus stop per hour
- 1) 8 minutes
- 2) 10 mintues
- 3) 12 minutes
- 4) 14 minutes
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Ans. B
Explanation :
Due to stoppages, it covers 9 km less.
Time taken to cover 9 km = (9/54) hour
= (1/6)*60 minutes
= 10 minutes
17) 2 trains starting at the same time from 2 stations 200 km apart and going in opposite direction cross each other at a distance of 110 km from one of the stations. What is the ratio of their speed
- 1) 11:9
- 2) 13:9
- 3) 17:9
- 4) 21:9
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Ans. A
Explanation :
We know total distance is 200 Km
If both trains crossed each other at a distance of 110 km then one train covered 110 km and other 90 km [110+90=200km]
So ratio of their speed = 110:90 = 11:9
18) A man complete a journey in 10 hours. He travels first half of the journey at the rate of 21 km/hr and second half at the rate of 24 km/hr. Find the total journey in
- 1) 200 Km
- 2) 222 Km
- 3) 224 Km
- 4) 248 Km
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Ans. C
Explanation :
Let time taken to travel the first half = x hr
Then time taken to travel the second half = (10 - x) hr
Distance covered in the the first half = 21x [because, distance = time*speed]
Distance covered in the the second half = 24(10 - x)
Distance covered in the the first half = Distance covered in the the second half
So,
21x = 24(10 - x)
=> 45x = 240
=> x = 16/3
Total Distance = 2*21(16/3) = 224 Km [multiplied by 2 as 21x was distance of half way]
19) A Man travelled a distance of 61 km in 9 hours. He travelled partly on foot at 4 km/hr and partly on bicycle at 9 km/hr. What is the distance travelled on fo
- 1) 16 km
- 2) 14 km
- 3) 12 km
- 4) 10 km
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Ans. A
Explanation :
Let the time in which he travelled on foot = x hour
Time for travelling on bicycle = (9 - x) hr
Distance = Speed * Time, and Total distance = 61 km
So,
4x + 9(9-x) = 61
=> 5x = 20
=> x = 4
So distance traveled on foot = 4(4) = 16 km
20) In a flight of 600 km, an aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 200 km/hr and the time of flight increased by 30 minutes. What is the duration of the flight
- 1) 3 hours
- 2) 2.4 hours
- 3) 1.4 hours
- 4) 1 hour
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Ans. D
Explanation :
Let the duration of the flight be x hours.
Then
\begin{aligned}
\frac{600}{x}-\frac{600}{x + \frac{1}{2}} = 200 \\frac{600}{x}-\frac{1200}{2x+1} = 200 \x(2x+1) = 3 \2x^2 + x - 3 = 0 \=> (2x+3)(x-1)=0
\end{aligned}
Neglecting the negative value for x we get x = 1