Problema Solution
Mr. Martain traveled to a city 360 miles from his home for a meeting. Due to car trouble his average speeding returning was 13mph less than his speed going. if the total time for the round trip was 18 hours at what rate of speed did he travel to the city?
Answer provided by our tutors
let
v = the avg. speed going to the city, v>0
v - 13 = the avg. speed returning from the city ( his average speeding returning was 13 mph less than his speed going), v - 13 >0 or v > 13
d = 360 mi the distance traveled in one direction
t1 = the time spent going to the city
t2 = the time coming back from the city
t1 + t2 = 18 hr the total time for the round trip
since avg.speed = distance/time we have time = distance/avg.speed thus:
t1 = d/v
t2 = d/(v - 13)
plug the above values in t1 + t2 = 18
d/v + d/(v - 13) = 18
360/v + 360/(v - 13) = 18 multiply both sides by v(v - 13)/18
20(v - 13) + 20v = v(v - 13)
by solving we find:
v = 47.53 mph approximately
click here to see the step by step solution of the equation:
Mr. Martain traveled with 47.53 mph approximately to the city.