Need help fast

Only typed answer needed

Handwritten answer not allow

You stand at the top of your apartment while your little sister stands on the ground below you. You drop a ball from rest and see that she catches it 2.5 s later. Your sister then throws the ball up to you, such that it just comes to rest in your hand. What is the speed , in meters per second, with which your sister threw the ball? (ignore the air resistance)