Problema Solution
Two friends decided to meet in Chicago. Rob travels 130 miles in the same time that Carl travels 122 miles. Robs trip uses more interstate highways and he can average 4 mph more than Carl. What is Rob's average speed?
Answer provided by our tutors
let
v = Carl's average speed
v + 4 = Rob's average speed (he can average 4 mph more than Carl)
d1 = 122 mi the distance Carl traveled
d2 = 130 mi the ditance Rob traveled
since speed = distance/time we have time = distance/speed
we know that they both traveled the same times:
d1/v = d2/(v + 4)
122/v = 130/(v + 4)
by solving we find
v = 61 mph
click here to see the step by step solution of the equations:
v + 4 = 61 + 4 = 65 mph
Rob's average speed is 65 mph.