How high does your vertical have to be to touch 10 feet?

I am 5'10 and 138lb.. I have a 11 inch reach, and when I jump I can touch 32. So that means I have 21 inch vertical..

How high do I have to jump to touch 10 feet, I wanna touch it in like 3 months, what should I do that wont effect your back?

well I mean you can do the math to see how much your vert has to be. but to be able to jump higher you need to strengthen your quads and more importantly your calves. you can do a lot of things to do this but once simple and easy exercise is calf dips and raises.

all you have to do is go to the stairs and stand on the edge of one (the higher the stair the more garvity will pull you too) and step out as far as you can so the tips of your toes are still on the step. dip low and raise you rbody back up. you'll feel it in your calves .

and another good easy thing to try is holding some weight in a backpack and just stand and do calf raises. go up on your tippy toes hold it or about 4-5 seconds and go back down. do as many reps as you can and you will see an improvement. im 6'1 and in 12th grade I could dunk a 12 lb shotput.