Problems on Trains - Quantitative Aptitude (MCQ) questions for Q. 21147

Q.  A boy sitting in a train counts the electricity poles along the line as he passes them. If they are 40 m apart and the speed of the train is 48 km/h, how many poles does he pass per minute ?
- Published on 22 Apr 16

a. 14
b. 19
c. 21
d. 24
e. None of these

ANSWER: 21
 
Speed of train = 48 km/h = (48 * 1000)/60 m/minute
= 800 m/minute
Thus we have to find the number of poles situated along a distance of 800 with each pole at a distance of 40 m from each other.

|--------40 m-------|--------40 m ---------|
Consider a distance of 80 m. There are 3 poles situated along this distance as shown.
Thus number of poles = 80/40 + 1 = 2 + 1 = 3
Similarly along a distance of 900 m, number of poles situated
= 800/40 + 1 = 21

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