SOLUTION: Justin can run 10 km in the same amount of time that Leo can run 12 km. if Leo can run 1 kph faster than Justin, how fast can Leo run?
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-> SOLUTION: Justin can run 10 km in the same amount of time that Leo can run 12 km. if Leo can run 1 kph faster than Justin, how fast can Leo run?
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Question 1179934: Justin can run 10 km in the same amount of time that Leo can run 12 km. if Leo can run 1 kph faster than Justin, how fast can Leo run? Found 2 solutions by mananth, greenestamps:Answer by mananth(16946) (Show Source):
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Justin can run 10 km in the same amount of time that Leo can run 12 km. if Leo can run 1 kph faster than Justin, how fast can Leo run?
let Justin's speed be x km/h
Leo's speed = x+1 km/h
Justin's time = 10/x
Leo's time = 12/(x+1)
Both times are equal
10/x = 12/(x+1)
10(x+1) =12x
10x +10 =12x
2x=10
x= 5 Justin's speed
Leo's speed = 6 km/h
The response from the other tutors solve the problem by using the "times are the same" equation:
Justin's time = 10km/x mph
Leo's time =12km/(x+1)mph
That leads to a relatively easy solution using basic algebra.
Setting up the problem using a different proportion makes solving the problem easier.
Since the times are the same, the ratio of distances is equal to the ratio of speeds:
Simplify the numerical fraction on the left:
That equation COULD be solved using formal algebra; but it can also be solved by inspection: x=5 makes the fraction on the right 6/5, which is the same as the fraction on the left.
