Yolanda throws a sphere up in the air from the top of a building. After tt seconds, the height of the sphere above the ground is hh feet, where h=−16t^2+40t+78. After how many seconds does the sphere hit the ground?

When the sphere hits the ground , h = 0

0 = -16t^2 + 40t+ 78 Use Quadratic Formula to solve for 't' ....throw out negative values for 't'