SOLUTION: if you drive a car 135 miles and have a mean of a certain speed. if the mean speed had been 4 mph more, you could have traveled 144 miles in the same time. what was the mean speed?

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: if you drive a car 135 miles and have a mean of a certain speed. if the mean speed had been 4 mph more, you could have traveled 144 miles in the same time. what was the mean speed?      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 908074: if you drive a car 135 miles and have a mean of a certain speed. if the mean speed had been 4 mph more, you could have traveled 144 miles in the same time. what was the mean speed?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
if you drive a car 135 miles and have a mean of a certain speed.
if the mean speed had been 4 mph more, you could have traveled 144 miles in the same time.
what was the mean speed?
:
let s = the mean speed
then
(s+4) = the faster speed
:
Write a time equation, time = dist/speed
actual time = faster speed time
135%2Fs = 144%2F%28%28s%2B4%29%29
Cross multiply
144s = 135(s+4)
144s = 135s + 540
144s - 135s = 540
s = 540/9
s = 60 mph is the mean speed
:
;
you can confirm this, find the actual time at each speed, should be the same
135/60 = 2.25 hr
144/64 = 2.25 hr