Problema Solution
Mary walked from point A to B at 6km/h and returned at 4km/h. It took her 5 hours. Find the distance between A and B.
Answer provided by our tutors
let
d = the distance between A and B
v1 = 6 km/h the walking speed from A to B
t1 = the time of the walk from A to B
v2 = 4 km/h the walking speed from B to A (the return trip)
t2 = the time of the walk from B to A
since speed = distance/time => time = distance/speed
t1 = d/v1
t1 = d/6
t2 = d/v2
t2 = d/4
It took her 5 hours
t1 + t2 = 5
plug t1 = d/6 and t2 = d/4 into the last equation
d/6 + d/4 = 5
by solving the equation we find
d = 12 km
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the distance between A and B is 12 km.