A moving cargo train takes 5 minutes to pass a polar bear moving in th

Question

A moving cargo train takes 5 minutes to pass a polar bear moving in the opposite direction at the speed of 15 miles per hour. If the length of the train is 1.25 miles, what is the speed of the train ?

A. 20 miles per hour

B. 21.25 miles per hour

C. 30 miles per hour

D. 45 miles per hour

E. 60 miles per hour

chetan2u · Answer

Question seems to be faulty.

It should be in same direction and not opposite direction.

The bear will cover  5*\frac{15}{60}  or 1.25 miles in 5 minutes.

1) Opposite direction: Speeds will get added....T——><——-B => T+B
If the train length is 1.25 miles, the bear itself covers the distance of 1.25 miles, meaning the train is stationary. 
So 1.25 is covered at a speed of T+15
 \frac{1.25}{T+15}=\frac{5}{60} 
 1.25*12=T+15........T=15-15=0

2) Same direction: Speeds will be subtracted........T——>B——> => T-B
So 1.25 is covered at a speed of T-15
 \frac{1.25}{T-15}=\frac{5}{60} 
 1.25*12=T-15........T=15+15=30

DrVanNostrand · Answer

The question seems to be wrong for the reason mentioned in the previous reply. If they move in the in the opposite direction, the train seems to be stationary which is in conflict with the question.

A moving cargo train takes 5 minutes to pass a polar bear moving in th

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