[maprikel (OP)]

I am an aging volleyball player and my vertical jump is not what it used to be.  General conditioning and strength are key factors.  My question is about how much higher I could jump if I lost some weight.  My thinking is my legs have the strength to lift my body 15 inches, if I lost weight (assuming all other conditions are the same) how much higher could I jump?
Current weight 225 lbs
Loose 10 lbs
Loose 20 lbs
Mark

[lyner]

All things being equal, the gravitational potential from your kinetic energy when you leave the ground would be the same for the new improved mass you will have achieved.
Lose 10lbs, you should be able to jump 225/215 times as high (about 5% better) and with 20lb loss, 225/205 times (about 10% better).
But that presupposes that  you would actually be able to launch  at the higher speed. You might need to train your muscles etc to make full use of  your improvement in mass.