Here are the returns on two stocks.

Digital Cheese Executive Fruit

January $+19+8$

February $3+1$

March $+5+4$

April $+7+17$

May $4+2$

June $+3+4$

July $23$

August $82$

Required:

a$-1.$ Calculate the variance and standard deviation of each stock.

a$-2.$ Which stock is riskier if held on its own?

b$.$ Now calculate the returns in each month of a portfolio that invests an equal amount each month in the two stocks.

c$.$ Is the variance more or less than halfway between the variance of the two individual stocks?