a. A portfolio is invested in a very large number of shares ( n is large). The standard deviation of the residual return of any of these stocks is not so large as to overwhelm the rest of the portfolio. However, one-half of the portfolio is invested in stock 1, and the rest of the portfolio is equally divided among the other n  1 shares. Is this portfolio well diversified?

b. Another portfolio also is invested in the same n shares, where n is very large. Instead of equally weighting with portfolio weights of 1/ n in each stock, the weights in half the securities are 1.5/ n while the weights in the other shares are .5/ n. Is this portfolio well diversified?