Question 1100086:  1. Mary departs for school on a bicycle at an average rate of 6 miles per hour. Her sister Kate, running late, leaves 15 minutes later and cycles at twice that speed. How long will it take Kate to catch  
 Answer by ankor@dixie-net.com(22740)      (Show Source): 
You can  put this solution on YOUR website! 1. Mary departs for school on a bicycle at an average rate of 6 miles per hour. 
 Her sister Kate, running late, leaves 15 minutes later and cycles at twice that speed. 
 How long will it take Kate to catch Mary? 
: 
We are dealing in mph, change 15 min to .25 hrs 
let t = Kate's travel time 
then 
(t+.25) = Mary's travel time 
: 
When K catches M, they will have traveled the same distance 
Write a distance equation, dist = speed * time 
12t = 6(t+.25) 
12t = 6t + 1.5 
12t - 6t = 1.5 
6t = 1.5 
t = 1.5/6 
t = .25 hrs or 15 min for K to catch M 
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