+0  
 
0
88
2
avatar

Antti entered a 10-kilometer race. His goal is to finish in one hour. He starts off sprinting, and completes the first 2 kilometers of the race at an average speed of 12 kilometers per hour. To achieve his goal of a one-hour finish time, what average speed must Antti maintain for the last 8 kilometers of the race? Enter your answer as a number in decimal form, without units. Please help finish

Guest May 6, 2017
Sort: 

2+0 Answers

 #1
avatar+75352 
+1

Antti entered a 10-kilometer race. His goal is to finish in one hour. He starts off sprinting, and completes the first 2 kilometers of the race at an average speed of 12 kilometers per hour. To achieve his goal of a one-hour finish time, what average speed must Antti maintain for the last 8 kilometers of the race? Enter your answer as a number in decimal form, without units. Please 

 

Let's first find out how many minutes it took him to run the first 2 K....

 

Since   Distance / Rate  = Time....we have

 

2K / ( 12 k/hr )   =   1/6 hr

 

 

So....this means that he must run the last 8K in 5/6 hr....so we have

 

Distance /Time   = Rate

 

8k / (5/6) hr  =    

 

8 / (5/6)  =

 

8 * (6/5)  =

 

48/5  =  

 

9.6  k / hr

 

 

cool cool cool

CPhill  May 6, 2017
 #2
avatar
+1

Thanks

Guest May 6, 2017

16 Online Users

avatar
avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details