Question

Two trains, traveling towards each other, left from two stations that are $900$ miles apart, at $4pm$. If the rate of the first train is $72$mph and rate of the second train is $78$mph, at what time (T pm) will they pass each other, find T ?

Answer 1

After $t$ hours the two trains will have travelled the distance D1 and D2 miles and as per the given information D1 = 72$t$ and D2 = 78$t$
After $t$ hours the total distance D travelled by the two trains will be,
D = D1+D2
D = 72$t$ + 78$t$
D = 150$t$
Given that the distance D is 900 miles, the trains will pass each other at,
150$t$ = 900
$t$ = 900/150
$t$ = 6 hours.
The two trains will pass each other 6 hours after the starting time of 4pm.
4pm + 6 hours = 10pm.
Ans : 10pm