In mid-2012, AOL Inc. had $200 million in debt, total equity capitalization of $3.1 billion, and an equity beta of 0.97 (as reported on Yahoo! Finance). Included in AOL's assets was $1.6 billion in cash and risk-free securities. Assume that the risk-free rate of interest is 2.9% and the market risk premium is 3.9%.

a. What is AOL's enterprise value? Correct answer is 1.7 billion

b. What is the beta of AOL's business assets? Correct answer is 1.77

c. What is AOL's WACC? Correct answer is 9.803%

I know how to calculate a) and c), but not b).

In addition the same question has been asked before, but the answer to b) has been incorrect.