SOLUTION: A motorist travels 90km at 120km/hr , and 40km at 90km/hr . what is the average speed of the trip??

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: A motorist travels 90km at 120km/hr , and 40km at 90km/hr . what is the average speed of the trip??      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 344537: A motorist travels 90km at 120km/hr , and 40km at 90km/hr . what is the average speed of the trip??
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Rate*Time=Distance
.
.
.
R%2At=D
t=D%2FR
t%5B1%5D=90%2F120=3%2F4hr
t%5B2%5D=40%2F90=4%2F9hr
Total time for the trip was,
T=t%5B1%5D%2Bt%5B2%5D=3%2F4%2B4%2F9
T=27%2F36%2B16%2F36
T=43%2F36hr
Total distance for the trip was,
D%5Bt%5D=90%2B40
D%5Bt%5D=130km
So, the average speed was,
V%5Bave%5D=D%5Bt%5D%2FT=130%2F%2843%2F36%29=%28130%2A36%29%2F43
V%5Bave%5D=4680%2F43kph
or approximately
V%5Bave%5D=109kph