do not use exell, show the steps please i need the steps.

7-6. (Calculating expected rates of return and risk) (Related to Checkpoint 7.1 on page 232) B.J. Gautney Enterprises is evaluating a security. One-year Treasury bills are currently paying 2.9 percent. Calculate the following investment's expected return and its standard deviation. Should Gautney invest in this security? Probability .15 .30 .40 .15 Return -3% 2% 4% 6%