Question 20001: A student walks and jogs to college each day. The student averages 5 km/h walking and 9 km/h jogging. The distance from home to college is 8 km, and the student makes the trip in 1 hour. How far does the student jog?
Answer by suresh(20)   (Show Source):
You can put this solution on YOUR website! Let x be the distance travelled by walk.
Let y be the distance travelled by jog.
Given x + y = 8-----> (1) ( Since total distance is 8 km)
We know, time = distance / speed.
The average speed of the student by walk = 5 km/hr.
The average speed of the student by jog = 9 km/hr.
The time taken by walk = x/5 hr.
The time taken by jog = y/9 hr.
Total time taken by the student = 1 hr.
So, x/5 + y/9 = 1
9x + 5y =45 -----> (2)
Multiply (1) by 5, we get, 5x+5y=40 ----->(3)
Subtract (3) from (2), 4x = 5
x=5/4=1.25
Plug the value in (1), y = 8 - 1.25 = 6.75.
Hence the student jogs 6.75km.
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