SOLUTION: Find out the average speed of person who rides the first miles at therate of 8 miles an hour the next mile at the rate of 7.5 miles an hour and the third mile at the rate of tm5.5

Algebra ->  Average -> SOLUTION: Find out the average speed of person who rides the first miles at therate of 8 miles an hour the next mile at the rate of 7.5 miles an hour and the third mile at the rate of tm5.5       Log On


   

Question 945767: Find out the average speed of person who rides the first miles at therate of 8 miles an hour the next mile at the rate of 7.5 miles an hour and the third mile at the rate of tm5.5 miles an hour
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
D=R%2At
t=D%2FR
Time for mile 1:t%5B1%5D=1%2F8
Time for mile 2:t%5B2%5D=1%2F7.5=4%2F30
Time for mile 3:t%5B3%5D=1%2F5.5=2%2F11
So then for the 3 mile distance,
R=D%2Ft
R=3%2F%281%2F8%2B4%2F30%2B2%2F11%29
R=3%2F%28165%2F1320%2B176%2F1320%2B240%2F1320%29
R=3%2F%28581%2F1320%29
highlight%28R=3960%2F581%29mph