Assume the historical return for ABC Company is 11.5% and its beta is .5. Further assume that the risk-free rate of return is 3% and the standard deviation is 30%. Based on these factors (using the Capital Asset Pricing Model) calculate the cost of equity.

A. 8.5%

B. 4.25%

C. 6.25%

D. 7.30%

I need the excel formula for this. The answer should be 4.25.