SOLUTION: An old car has to travel a 2-mile route, uphill and down. Because it is so old, the car can climb the first mile-the ascent-no faster than an average speed of 15 mi/h. How fast doe

Question 249425: An old car has to travel a 2-mile route, uphill and down. Because it is so old, the car can climb the first mile-the ascent-no faster than an average speed of 15 mi/h. How fast does the car have to travel the second-on the descent it can go faster, or course-in order to achieve an average speed of 30 mi/h for the trip?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
An old car has to travel a 2-mile route, uphill and down.
Because it is so old, the car can climb the first mile-the ascent-no faster than an average speed of 15 mi/h.
How fast does the car have to travel the second-on the descent it can go faster, or course-in order to achieve an average speed of 30 mi/h for the trip?
:
This is impossible; the time to go 1 mi at 15 mph, is the same as 2 mi at 30 mph
You have to go the 2nd mile in 0 time, that's fast!
:
But let's assume that it is a legitimate problem:
:
Let s = the speed down hill
:
Time up hill + time down hill = total time
+ =
:
Multiply equation by 30s; results
2s + 30 = 2s
:
Obviously this is not possible
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