7. The length of the train that takes 8 seconds to pass a pole when it runs at a speed of 36 km/hr, is :
a. 88 meters
b. 45 meters
c. 48 meters
d. 80 meters

8. A train 280 metres long is moving at speed of 60 km/hr. The time taken by the train to cross a platform 220 metres long is :
a. 20 seconds
b. 25 seconds
c. 30 seconds
d. 35 seconds

Answer: C

Explanation:
Speed of the train = $\left( {60 \times \displaystyle\frac{5}{{18}}} \right)$ m/sec = $\left( {\displaystyle\frac{{50}}{3}} \right)$ m/sec
Time taken by the train to cross the platform = Time taken by it to cover (280 + 220) meters = 500 meters.
$\Rightarrow \dfrac{{500}}{{\left( {50/3} \right)}}$ = $\left( {500 \times \displaystyle\frac{3}{{50}}} \right)$sec = 30 sec.

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9. A train 50metres long passes a platform 100 metres long in 10 seconds. The speed of the train is :
a. 10 km/hr
b. 15 km/hr
c. 54 km/hr
d. 100km/hr

Answer: C

Explanation:
Distance covered by train in 10 sec. = (50+100)m=150 m
Speed = $\left( {\displaystyle\frac{{150}}{{10}}} \right)$ m/sec = $\left( {15 \times \displaystyle\frac{{18}}{5}} \right)$ km/hr=54 km/hr

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10. A person sees a train passing over 1 km long bridge. The length of the train is half that of the bridge. If the train clears the brdige in 2 minutes, the speed of the train is :
a. 50 km/hr
b. 45 km/hr
c. 60 km/hr
d. 30 km/hr

Answer: B

Explanation:
Distance covered in $\left( {\displaystyle\frac{2}{{60}}} \right)$ hr = $\left( {1 + \displaystyle\frac{1}{2}} \right)$ km = ${\displaystyle\frac{3}{2}}$ km
Distance covered in 1 hr = $\left( {\displaystyle\frac{3}{2} \times \displaystyle\frac{{60}}{2}} \right)$ km = 45 km
So, speed of the train = 45 km/hr.

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11. A train 700 m long is running at the speed of 72 km per hour. If it crosses a tunnel in 1 minute, then the length of the tunnel is :
a. 500 m
b. 550 m
c. 600 m
d. 700 m

Answer: A

Explanation:
Speed = $\left( {72 \times \displaystyle\frac{5}{{18}}} \right)$ m/sec = 20 m/sec
Let the length of tunnel = x metres
Then, $\displaystyle\frac{{700 + x}}{{60}} = 20$
$ \Rightarrow 700 + x = 1200$ or x = 500 m

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12. A train 270 metres long is moving at a speed of 25 kmph. It will cross a man coming from the opposite direction at a speed of 2 km per hour in :
a. 36 seconds
b. 32 seconds
c. 28 seconds
d. 24 seconds

Answer: A

Explanation:
Relative speed = (25 + 2) km/hr = 27 km/hr = $\left( {27 \times \displaystyle\frac{5}{{18}}} \right)$ m/sec = $\left( {\displaystyle\frac{{15}}{2}} \right)$ m/sec.
Time taken by the train to pass the man =$\left( {270 \times \displaystyle\frac{2}{{15}}} \right)$ sec = 36 sec