Here are the percentage returns on two stocks.

Month Digital Cheese Executive Fruit

January $15\%5\%$

February $51$

March $73$

April $913$

May $62$

June $55$

July $44$

August $73$

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

Note: Do not round intermediate calculations. Round your answers to $1$ decimal places.

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

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

Note: Do not round intermediate calculations. Round your answers to $1$ decimal places.

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