Question Detail
An athlete runs 200 meters in 24 seconds. His speed is ?
- 10 km/hr
- 17 k/hr
- 27 km/hr
- 30 km/hr
Answer: Option D
Explanation:
\begin{aligned}
Speed = \frac{Distance}{Time} \\
= \frac{200}{24}m/sec = \frac{25}{3} m/sec \\
\frac{25}{3}*\frac{18}{5} km/hr = 30 km/hr
\end{aligned}
1. A thief is noticed by a policeman from a distance of 200 m. The thief starts running and the policeman chases him. The thief and the policeman run at the rate of 10 km and 11 km per hour respectively. What is the distance between them after 6 minutes ?
- 50 meter
- 100 meter
- 110 meter
- None of above
Answer: Option B
Explanation:
Relative speed of the thief and policeman = (11 – 10) km/hr = 1 km/hr
Distance covered in 6 minutes =
\begin{aligned}
\frac{1}{60}*6 = \frac{1}{10} \\
= 100 meters
\end{aligned}
So distance between them after 6 minutes = 200 - 100
= 100 meters
2. A train covers a distance in 50 minutes, if it runs at a speed of 48kmph on an average. Find the speed at which the train must run to reduce the time of journey to 40 minutes.
- 50 km/hr
- 60 km/hr
- 65 km/hr
- 70 km/hr
Answer: Option B
Explanation:
We are having time and speed given, so first we will calculate the distance. Then we can get new speed for given time and distance.
Lets solve it.
Time = 50/60 hr = 5/6 hr
Speed = 48 mph
Distance = S*T = 48 * 5/6 = 40 km
New time will be 40 minutes so,
Time = 40/60 hr = 2/3 hr
Now we know,
Speed = Distance/Time
New speed = 40*3/2 kmph = 60kmph
3. A person crosses a 600 meter long street in 5 minutes. What is the speed in Km/hr
- 6.2 km/hr
- 7.2 km/hr
- 8.2 km/hr
- 9.2 km/hr
Answer: Option B
Explanation:
Two things to give attention on this question.
First time is in minutes, we need to change it to seconds to get speed in m/sec, then we need to get the final answer in km/hr.
So lets solve this.
\begin{aligned}
Speed = \frac{Distance}{Time} \\
Distance = 650 meter \\
Time = \text{5 minutes} = 300 sec \\
Speed = \frac{600}{300} = 2 m/sec \\
=> 2*\frac{18}{5} km/hr = 7.2 km/hr
\end{aligned}
4. 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 point.
- 6 hours 24 mins
- 6 hours 21 mins
- 6 hours 18 mins
- 6 hours 15 mins
Answer: Option 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
5. 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 speeds ?
- 11:9
- 13:9
- 17:9
- 21:9
Answer: Option 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