Problema Solution
During a 65 km ride, I cycled 7 km per hour faster than my sister. I finished 45 minutes ahead of her. What was my speed?
Answer provided by our tutors
let
v = the speed of my sister
v + 7 = my speed (7 km per hour faster than my sister)
d = 65 km the distance of the ride
t = the time of my sister
t - 45/60 = my time
since distance = speed*time we have
v*t = d
vt = 65 => t = 65/v
(v + 7)(t - 45/60) = 65
plug t = 65/v into the least equation
(v + 7)(65/v - 45/60) = 65
by solving we find
v = 21.38 km per hour
click here to see the step by step solution of the equation
v + 7 = 21.38 + 7 = 28.38 km/hr
my speed was 28.38 km/hr.