Tennis ball bouncing on the floor - How high does it bounce?

1. The problem statement, all variables and given/known data

A tennis ball bounces on the floor three times. If each time it loses 21% of its energy due to heating, how high does it bounce after the third time, provided we released it 4.6 from the floor?


2. Relevant equations



3. The attempt at a solution

I just can't deal with energy. Do I have to make use of mechanical energy?

 

I'd need to know the weight of the ball to do that, and all I'm given is how much energy the ball loses due to heat after each bounce, and how high the ball is when I throw it.