SOLUTION: sam salesman has to get from point a to point b in 2.75 hours and 200 miles. sam takes the interstate and averages around 75 mph for the first 120 miles of his journey. what averag

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Question 1144803: sam salesman has to get from point a to point b in 2.75 hours and 200 miles. sam takes the interstate and averages around 75 mph for the first 120 miles of his journey. what average speed must sam drive during the remainder of the time in order to get there in time ?
Found 2 solutions by greenestamps, josgarithmetic:
Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


The first part of the journey is 120 miles at 75mph. That leaves 80 miles for the second part.

(1) Determine the amount of time for the first part of the journey (time = distance divided by rate)

(2) Determine the amount of time remaining (total time 2.75 hours)

(3) Determine the speed required for the second part (speed = distance divided by time)

Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
PART              SPEED       TIME         DISTANCE

interstate           75        120/75         120

remainder            r          80/r           80

TOTALS                          2.75          200

120%2F75%2B80%2Fr=2.75
Solve for r.