show excel formulas in calculations and =formulatext or explain

The following are the monthly rates of return for The South African Biscuit House and for The Northern Electric Company during a six-month period. Calculate the following. (a) Average monthly rate of return R for each stock (b) Standard deviation of returns for each stock (c) Covariance between the rates of return (d) The correlation coefficient between the rates of return What level of correlation did you expect? How did your expectations compare with the calculated correlation? Would these two stocks be good choices for diversification? Why or why not