#### Answer

7.7 m/s

#### Work Step by Step

Find the time the ball is in the air from equation 2.11b applied to the vertical motion. The acceleration is g, the initial vertical velocity is zero, and the ball is displaced 7.5 m vertically. The time is 1.237 s.
Calculate the horizontal displacement as the horizontal velocity multiplied by this time:
(Vx)(1.237 s) = 9.5 m.
Solve for the initial horizontal velocity of 7.7 m/s.