Problema Solution
A trucker drove 160 miles to make a delivery and returned home the same route. Because of fog, his average speed on returning was 20 mph less than his speed going. If the return took 4 hours longer, how fast did he drive in each direction?
Answer provided by our tutors
let
d = 160 mi
v = the speed going, v>0
v - 20 = the speed returning
t = the time going,t >0
t + 4 = the time returning
since speed = distance/time we have distance = speed*time:
when the truck is going:
v*t = d
t = d/v
t = 160/v
when the truck s returning:
(v - 20)(t + 4) = d
(v - 20)(160/v + 4) = 160
by solving we find:
v = 40 mph
click here to see the step by step solution of the equation:
v - 20 = 40 - 20 = 20 mph
the speed driving to the location is 40 mph.
the speed returning is 20 mph.