SOLUTION: Darren drives to school in rush hour traffic and averages 21 mph. He returns home in mid-afternoon when there is less traffic and averages 42 mph. What is the distance between his

Question 1094907: Darren drives to school in rush hour traffic and averages 21 mph. He returns home in mid-afternoon when there is less traffic and averages 42 mph. What is the distance between his home and school if the total traveling time is 1hr30min?

Found 4 solutions by greenestamps, josgarithmetic, josmiceli, MathTherapy:
Answer by greenestamps(13200)   (Show Source): You can put this solution on YOUR website!

His afternoon speed is exactly twice his morning speed, so the afternoon trip takes exactly half as long as the morning trip.

Since the total driving time was an hour and a half, the morning trip took an hour and the afternoon trip took half an hour.

Using the time and average speed for either the morning or afternoon trip shows the driving distance to be 21 miles:
or
Answer by josgarithmetic(39617)   (Show Source): You can put this solution on YOUR website!

SPEED TIME DISTANCE GOING 21 d/21 d RETURN 42 d/42 d Total 1&1/2

Solve for d.
Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!
Let = travel time in hrs going to school
= travel time in hrs going home
Let = the one-way distance in miles to school
---------------------------------------------
Equation for going to school:
(1)
Equation for going home:
(2)
----------------------------
Set (1) = (2)

---------------------
(1)
(1)
(1)
The distance between home and school is 21 miles
----------------------
check:
(2)
(2)
(2)
(2)
OK
Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!

Darren drives to school in rush hour traffic and averages 21 mph. He returns home in mid-afternoon when there is less traffic and averages 42 mph. What is the distance between his home and school if the total traveling time is 1hr30min?

Let distance be D
Then time taken to get to school =
Time taken to get home =
We then get the following TIME equation:
2D + D = 63 ----- Multiplying by LCD, 42
3D = 63
D, or distance =
How easy was that?
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