### Home > INT3 > Chapter 9 > Lesson 9.1.2 > Problem9-15

9-15.

David Longshot is known for his long golf drives. At the driving range he hit a golf ball $250$ yards and estimated that the ball reached a maximum height of $15$ yards.

1. Use a quadratic function to model the path of the golf ball.

$f\left(x\right) = a\left(x − h\right)^{2} + k$

Use the maximum-point coordinates to replace some variables in the equation above.

Substitute $\left(0, 0\right)$ for $x$ and $y$ to solve for the slope.

2. David’s brother, Dwayne, was also at the driving range and hit a ball according to the table below. Which ball traveled farther horizontally? Which ball went higher in the air?

 Horizontal distance (yd) Height (yd) $0$ $0$ $20$ $5.5$ $60$ $13.5$ $180$ $13.5$ $220$ $5.5$

Sketch Dwayne's projection and notice how much farther his ball can travel past $220$ yards.

David's ball traveled farther at $250$ yards while Dwayne's ball traveled $240$ yards.
How high did Dwayne's ball go?