SOLUTION: Sarah ran 5 miles at a constant speed. She then reduces her speed by 3 miles per hour and walked the last 2 miles at the reduced speed. If her total workout took 2 hours, find her

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Sarah ran 5 miles at a constant speed. She then reduces her speed by 3 miles per hour and walked the last 2 miles at the reduced speed. If her total workout took 2 hours, find her       Log On


   

Question 721111: Sarah ran 5 miles at a constant speed. She then reduces her speed by 3 miles per hour and walked the last 2 miles at the reduced speed. If her total workout took 2 hours, find her running speed.
Answer by josgarithmetic(39613) About Me  (Show Source):
You can put this solution on YOUR website!
Let r = rate at which she ran.

________________speed__________time____________distance
Ran______________r____________(___)_____________5
Walked___________r-3__________(___)_____________2
Total__________________________2________________7


Time information is still mssing, and maybe that information would be useful in the solution to find r. The total time is the sum of the time spent running and walking. Use speed*time=distance idea to find time expressions.

________________speed__________time____________distance
Ran______________r____________(5r)_____________5
Walked___________r-3__________(2%2F%28r-3%29)_____________2
Total__________________________2________________7

Most of the solution for this problem is to obtain this equation, which the table helps to develop:
highlight%285r%2B2%2F%28r-3%29=2%29, so now just solve for r.