Problema Solution
A train leaves little rock traveling 90 kilometers per hour. Another train leaves at the same time and travels south at 65 kilometers per hour. How long will it take them to be 620 kilometers apart?
Answer provided by our tutors
Let
v1 = 90 km/h be the speed of the first train traveling north
v2 = 65 km/h be the speed of the second train traveling south
After 't' time they will be 620 km apart. We need to find t non-negative number.
After t time
the first train has traveled v1*t = 90*t km
the second train has traveled v2*t = 65*t km
Since the trains move in opposite direction the total distance between them will be sum of the first trains distance and second trains distance:
v1*t + v2*t = 620
90*t + 65*t = 620
155*t = 620
t = 620/155
t = 4 hours
The trains need 4 hours to be 620 km apart.