They're not correct.
* Seperate the question.
All philosophers are cooks: That is all $x$ who is a philosopher is also a cook. $\forall x (Px \implies Cx)$
All cooks are philosophers: That is all $x$ who is a cook is also a philosopher.$\forall x (Cx \implies Px)$
If all philosophers cooks, then all cooks are philosophers: $(\forall x (Px \implies Cx)) \implies (\forall y (Py \implies Cy))$
* Again seperate:
Only philosophers are cooks. That is, if there is noone who is cook but not philosopher. $\
eg\exists x(Cx \land \
eg Px)$
We made the second part in the previous question. Then the answer is:
$(\
eg\exists x(Cx \land \
eg Px)) \implies (\forall y (Py \implies Cy))$
* All philosophers are wise: $\forall x (Px \implies Wx)$
Andre (I suppose it's not John but Andre) is a philosopher: $Pa$
He (Andre) is wise: $Wa$
Then the answer is: $((\forall x (Px \implies Wx)) \land Pa )\implies Wa$