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A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively. What is the speed of the train?

A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively. What is the speed of the train?
A.69.5 km/hrB.70 km/hr
C.79 km/hrD.79.2 km/hr

Answer: Option D
Explanation:
Let the length of the train be x metres and its speed by y m/sec.
Then,x= 8     =>     x = 8y
y
Now,x + 264= y
20
=> 8y + 264 = 20y
=> y = 22.
Therefore Speed = 22 m/sec =(22 x18(km/hr = 79.2 km/hr.
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