I'm having a little trouble with this problem?

Gerald wants to know how fast he can throw a ball, so he hangs a 2.30 kg target on a rope from a tree. He picks up a 0.50 kg ball of putty and throws it horizontally against the target. the putty sticks to the target and the putty and the target swing up a vertical distance of 1.50 m from its original position. How fast did gerald throw the ball of putty?