help me do this with excel. i need to confirm my answer and also know how to do this on excel

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rockwell fianial Inc.'s stock has a 25% chance of producing a 16% return, a 50% chance of producing a 12% return, and a 25% chance of producing a -18% return.

a. What is the firm's expected rate of return?

b. What is the variance on the firm's return?

c. What is the standard deviation on the firm's return?

Do not round vour intermediate calculations.

( EXCEL APPROACH ONLY)