posted by mich on .
Two drivers travel 150 miles on a
freeway and then stop at a wayside rest area. The
first driver travels 5 miles per hour faster and arrives
1/7 hour ahead of the second. Find the average speed
of each car.
Let the speed of the faster car be V. The other is then V - 5 (in mph)
The travel times are 150/V and 150/(V-5)
150/(V-5) - 150/V = 1/7 hour
Solve that equation for V. That will require solving a quadratic. I'd prefer to take a guess or two.
If V = 75,
2.143 - 2.000 = 0.143 = 1/7
Therefore the speeds are 75 and 70 mph