Chapter 1.1, Problem 54E

For the following exercises, use a graphing utility to graph the curve represented by the parametric equations and identify the curve from its equation.

54. An airplane traveling horizontally at $100\text{m/s}$ over flat ground at an elevation of 4000 meters must drop an emergency package on a target on the ground. The trajectory of the package is given by $x=100t,y=-4.9t^2+4000,t\ge 0$ where the origin is the point on the ground directly beneath the plane at the moment of release. How many horizontal meters before the target should the package be released in order to hit the target?