run of 10km North and then a bike of 120km West. Determine running speed if she cycles 10 times faster than she runs and the race took her 4 hours to complete.

Question

The goal is to determine the running speed of the person. 

Answer 1

Good afternoon Annie,

 

You'll set up 2 variables, have 2 equations and use substitution to solve

 

x = time spent running

 

y = time spent cycling

 

speed running = distance/time = 10/x

 

speed cycling = 120/y

 

x + y = 4 hours

 

y = 4 -x

 

speed cycling is 10 times the speed running

 

120/y = 10(10/x)

 

now substitute

 

120/(4-x) = 100/x

 

Cross multiply

 

120x = 400 - 100x

 

220x = 400

 

x= 20/11

 

so speed running = 10÷(20/11) = 5.5 km/hr

 

Have a good day

 

:)