The standard deviation of a portfolio (1 minute): can never be less than the standard deviation of the most risky security in the portfolio. must be equal to or greater than the lowest standard deviation of any single security held in the portfolio. is an arithmetic average of the standard deviations of the individual securities which comprise the portfolio. can be less than the standard deviation of the least risky security in the portfolio. is a weighted average of the standard deviations of the individual securities held in the portfolio.