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
+130081 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
