A stock has a price of $$70,$ which can later be $$73$ or $$64$ with different probabilities. The options, with exercise price $$70,$ are valued at $$1\mathrm{.}11($call$)$ and $$1\mathrm{.}20($put$).$ For all range of probabilities:

a$.$ Calculate the expected return and standard deviation for the stock.

b$.$ Calculate the expected returns and standard deviation for a covered call and protective put portfolio.

c$.$ How do the standard deviation of these three alternatives compare?

d$.$ For which combination of probabilities each alternative have a positive return?