Jamie is biking 400 kilometers on a mountain bike. Her bike has an odometer that tells her how far she's gone, as well as a timer which tells her how long she's been riding. The first 4 hours of riding are over very difficult terrain, and she only covers 40 kilometers. What is her average speed over the 4 hours? Do you think that she traveled exactly this speed for 4 hours, or that her speed varied?

Her average speed is 10 km/hr and is not constant throughout the 40 km journey.

Step-by-step explanation:

Total distance covered by Jamie = 40 km

Total time taken by her = 4 hours

According to the question:

The first 4 hours of riding are over very difficult terrain.

And we have to find the average speed.

Formula :

Average speed = Ratio of total distance covered and total time taken.

Plugging the numeric values we will find the average speed.

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So the average speed of Jamie is 10 km/hr.

Average speed doesn't mean that the body (object) / vehicle will travel, exactly with that speed.

Average speed is just the estimation that in and around most of the speed will be closest to the average values.

Jamie's speed have varied and not constant.

the answer is  

c.

14,469 cubic feet

i know this one is right