SOLUTION: Please help me solve this word problem. If you start out a 395 mile trip setting your cruise control to a constant speed of 70 mph, how many hours into the trip do you need to kick

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Question 698045: Please help me solve this word problem. If you start out a 395 mile trip setting your cruise control to a constant speed of 70 mph, how many hours into the trip do you need to kick it up to 75 mph in order to arrive at your destination in exactly 5.5 hours?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
If you start out a 395 mile trip setting your cruise control to a constant speed of 70 mph, how many hours into the trip do you need to kick it up to 75 mph in order to arrive at your destination in exactly 5.5 hours?
:
Let t = travel time until you must increase speed to 75
then
(5.5-t) = time traveling at 75 mph
:
Write a distance equation
75(5.5-t) + 70t = 395
412.5 - 75t + 70t = 395
-5t = 395 - 412.5
5t = 17.5
t = 17.5/5
t = 3.5 hrs travel time when speed is increase to 75
:
:
Confirm this, find the distance at each speed
75*2 = 150 mi
70*3.5 = 245 mi
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total dist: 395 mi