The stock of a technology company has an expected return of 15% and a standard deviation of 20% 10) The stock of a pharmaceutical company has an expected return of 13% and a standard deviation of 18%. A portfolio consisting of 50% invested in each stock will have an expected return of 14 % and a standard deviation (They are not perfectly positively correlated)

A) the average of 20% and 18%. B) less than the average of 20% and 18%. C) the answer cannot be determined with the information given.

D) greater than the average of 20% and 18%.

I know the answer is B but I need to know how is it calculated ?