GIVING 30 POINTS!! A skateboard halfpipe is being designed for a competition. The halfpipe will be in the shape of a parabola and will be positioned above the ground such that its focus is 40 ft above the ground. Using the ground as the x-axis, where should the base of the halfpipe be positioned? Which equation best describes the equation of the halfpipe?

y = (1/80)x^2 +20

Step-by-step explanation:

Assuming the halfpipe is only useful if the curve opens upward, the "base" (vertex) must be below the focus, so cannot be at (0, 40).

Apparently, the ground is supposed to be the directrix of the curve. Then the vertex is halfway between the focus and the ground, so is at (0, 20). The focus-vertex distance (p) is then 40-20 = 20 so the coefficient of the squared term is 1/(4p) = 1/(4·20) = 1/80.

For a vertex of (0, 20) and a vertical scale factor of 1/80, the equation of the curve is y = (1/80)x^2 +20

use an equation of ratios to determine the amount of gas needed to fill the tank.

    0.2             0.8

  =    

288.75             x

                                                              231 gal

so, 0.2x = (0.8)(288.75 gal), and x = = 1155 gal.

                                                                0.2

it would take 1155 gal. to fill the tank.

the cost would be

1155 gal         $3

* = $3465   (answer)

      1           1 gal

hope this you

no not all of them.

step-by-step explanation:

some of them have a square base.