Solve by a quadratic formula

Question

Mackenzie throws a ball off the empire building which is 1949 tall at a downwards velocity of 15 feet per second. How long will it take to hit Roderick on his back which is 5 feet on the ground?

Answer 1

-16t^2 -15t +1949 = 5

t = about 10.56392 seconds

graph the equation and find the positive x intercept

or do the tedious calculations with the quadratic formula

t = -30/16 + (1/16)sqr(225+ 64(1944))