Predicates and Quantifiers? suppose that the domain of variable x is the set of people, and f(x) = "x is friendly" , t(x)= "x is tall" and a(x) = "x is angry". Write the statement using these predicates and any needed quantifiers.
1) some people are not angry
2) all tall people are friendly
3) No friendly people are angry
My solutions:
1) $∃x\sim A(x)$
2) $∀xF(x)$
3) $\sim ∀x A(x)$
I'd like to know if my answers are right or wrong.  

As others have said, you second and third answers are wrong -- but more worryingly, they are quite fundamentally wrong, not mere slips. So this suggests that you ought to be looking at some good text book that tells you about translation into predicate calculus notation. Lots of intro logic books do this (P-t-r Sm-th's Introduction to Formal Logic is ok, I'm told!). For something freely available online which is very lucid, try Paul Teller's Modern Formal Logic Primer. Look at the first four (short!) chapters of Vol II.
