SOLUTION: A Car travels 240 mi. A second car, traveling 12 mph faster than the first, makes the same trip in 1 hour less time. Find the speed of each car
Question 359623: A Car travels 240 mi. A second car, traveling 12 mph faster than the first, makes the same trip in 1 hour less time. Find the speed of each car Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! A Car travels 240 mi. A second car, traveling 12 mph faster than the first,
makes the same trip in 1 hour less time. Find the speed of each car
:
Let s = speed of the slower car
then
(s+12) = speed of the faster
:
Write a time equation; time = dist/speed
:
Slow car time - fast car time = 1 hr - = 1
:
Multiply by s(s+12), results
240(s+12) - 240s = s(s+12)
:
240s + 2880 - 240s = s^2 + 12s
Combine as a quadratic equation on the right
0 = s^2 + 12s - 2880
Factors to
(s+60)(s-48) = 0
positive solution
s = 48 mph is the speed of the slower car
then
48 + 12 = 60 mph is the faster car
:
Check solution by finding the times of each - =
5 - 4 = 1 hr; confirms our solutions
