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# Antti entered a race help

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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
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#1
+77022
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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

CPhill  May 6, 2017
#2
+1

Thanks

Guest May 6, 2017

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