Problema Solution
A very long train is inching slowly along at a constant speed of 1mph. A person starts at the back of the train, running at a constant speed and reaches the front of the train in 0.07 hours, then turns around and runs to the back of the train in in 0.05 hours. How long is the train and how fast does the person run?
Answer provided by our tutors
distance = speed * time
we are given a train speed = 1 mph
let 'x' represent the length of the train in miles
let 'v' represent the speed of the runner in mph, then, measuring the runner's speed relative to the train, 'v+1' represents the runner's speed against the motion of the train and 'v-1' represents the runner's speed with the motion of the train
x = (v+1)0.05
x = (v-1)0.07
(v+1)0.05 = (v-1)0.07
v = 6
x = (6+1)0.05 = 0.35
the runner ran 6mph, the length of the train was 0.35 miles in length