Question

what is the ratio of pure tall and pure dwraf

Answer 1

F1 generation= TT:tt=Tt, Tt,Tt,Tt...= 1:4....& F2 generation=TT: Tt:tt= 1:2:1

Answer 2

ANSWER is

F1 = 100% tall Dd 
F2 = 75% tall (25%DD, 50% Dd) 25% short (dd) 
If you are expected to do this on an exam it would be worth practicing on your own too! We can't come help you during a test. This can be solved using a punnet square.