SOLUTION: Maria drove 150 miles from home to her parent's place. She drove at a constant speed. Later, she drove home 150 miles back again at a constant speed. Her drive back took .5 hours l
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Question 1102237: Maria drove 150 miles from home to her parent's place. She drove at a constant speed. Later, she drove home 150 miles back again at a constant speed. Her drive back took .5 hours longer because her speed was 10 miles per hour slower. How many hours did she drive TO her parents?
Found 2 solutions by josmiceli, greenestamps:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = her speed in mi/hr going to her parents
Let = her time in hrs to go to her parents
= her speed in mi/hr driving home
Driving home:
(2)
-----------------------------------
(2)
(2)
and
(1)
plug this into (2)
(2)
(2)
(2)
(2)
(2)
(2)
(2) ( by looking at it )
(2) ( can't have negative speed )
and
(1)
(1)
(1)
It took 2.5 hrs to drive to her parents house
-----------------------------------------
check:
(2)
(2)
(2)
(2)
OK
Get a 2nd opinion if needed
Answer by greenestamps(13198) (Show Source): You can put this solution on YOUR website!
The other tutor's answer is right. She checked it, and it worked, so it was right.
I think she did a lot more work than necessary to set up the problem.
Using her same notation of s and s-10 for the two speeds, we know that the difference between the time at the lower speed and the time at the higher speed was .5 hours. So
... which is the equation she ended up with after doing a lot more work.
The solution from there is the same.
The higher speed s is 60; the lower speed is 60-10=50. The time it took to drive to her parents (at the higher speed) was 150/60 = 2.5 hours.
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