Mike is training for a cross country bike ride. He rides his bike 60 miles, 66 miles, 70 miles, 60 miles, and 51 miles on the first five days of his training. How many miles does he need to ride on day 6 to average(mean) of 59 miles per day?

  c.  17.32 ft

Step-by-step explanation:

The attached graph provides a quick and easy solution.

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The equation of an ellipse with semi-major axis 50 and semi-minor axis 20 can be written as ...

  (x/50)^2 +(y/20)^2 = 1

We want to find the positive value of y when x=25.

  (25/50)^2 +(y/20)^2 = 1

  (y/20)^2 = 1 - 1/4 = 3/4 . . . . . subtract the constant on the left

  y = 20√(3/4) = 10√3 . . . . . . .square root and multiply by 20

The height of the bridge 25 feet from center is 10√3 ≈ 17.32 feet.