SOLUTION: greg drove at a constant speed in a rainstorm for 266 miles. he took a break, and the rain stopped. he then drove 230 miles at a speed that was 8 miles per hour faster than his pre
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Question 1109402: greg drove at a constant speed in a rainstorm for 266 miles. he took a break, and the rain stopped. he then drove 230 miles at a speed that was 8 miles per hour faster than his previous speed. if he drove for 12 hours, find the cars speed for each part of the trip Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! greg drove at a constant speed in a rainstorm for 266 miles.
he took a break, and the rain stopped.
he then drove 230 miles at a speed that was 8 miles per hour faster than his previous speed.
if he drove for 12 hours, find the car's speed for each part of the trip.
:
let s = the speed on the first part of the trip
(s+8) = the speed on the 2nd part of the trip
:
Write a time equation, time = dist/speed + = 12
multiply equation by s(s+8), cancel the denominator
266(s+8) + 230s = 12s(s+8)
266s + 2128 + 230s = 12s^2 + 96s
496s + 2128 = 12s^2 + 96s
0 = 12s^2 + 96s - 496s - 2128
12s^2 - 400s - 2128 = 0
simplify, divide by 4
3s^2 - 100s - 532 = 0
Use the quadratic equation to find s, a=3; b=-100; c=-532
the reasonable solution
s = 38 mph in the rain
then
38 + 8 = 46 mph after the rain
:
:
Check this, find the actual time at each speed
266/38 = 7 hrs
230/46 = 5 hrs
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tot. time 12 hrs
