Question

A man walking on a railroad bridge is 2/5 of the way along the bridge when he notices a train at a distance approaching at the constant rate of 45 mph . The man can run at a constant rate in either direction to get off the bridge just in time before the train hits him. How fast can the man run?

Answer 1

Answer:

9mph

Step-by-step explanation:

Given the following :

Speed of train = 45miles per hour

Distance of the man = 2/5

To avoid just about being hit by the train:

The main may run to the start point of the bridge towards the train = 2/5 length of the bridge, this is also when the train gets to the bridge

If the man runs forward away from the train, he has to cover a distance of (1 - 2/5) = 3/5 to avoid being hit, this is also when the train gets to the end of the bridge.

From here it could be inferred that :

The distance 3/5 ran by the man away from the bridge is equivalent to (3/5 - 2/5) =1/5, which seems to be moved by th etrain during the same period.

However, the only explanation for the discrepancy in length or distance is that the train moves faster than the man.

If the train's speed = 45mph

Then the train's speed is 5 times the speed of the man;

Man speed is thus;

(1/5) * 45 = 9mph