Problema Solution
Mary Smith drove from her apartment to her parents' house on a Saturday morning. She was able to average 60 mph because traffic was light. However, returning on Sunday night, she was able to average only 45 mph on the same route. The drive on Sunday took her 1.5 hr longer than the drive on Saturday. What is the distance between Mary's apartment and her parents' house?
Answer provided by our tutors
let
v1 = 60 mph the average speed of Mary on Saturday
v2 = 45 mph the average speed of Mary on Sunday
t1 = the time she drove on Saturday
t2 = the time she drove on Sunday
the drive on Sunday took her 1.5 hr longer than the drive on Saturday
t2 = 1.5 + t1
since the average speed = the total distance passed/the total time needed we have v = d/t => d = v*t
60*t1 = 45*(t1 + 1.5)
15*t1 = 1.5
t1 = 1/10 hr
now we can find the distance
d = t1*v1 = (1/10)*(60) = 6 miles
the distance between Mary's apartment and her parents' house is 6 miles.