The following table summarizes the percentage changes in operating income, percentage changes in revenue and betas for four pharmaceutical firms.

Firm

% Change in Revenue

% Change in Operating Income

Beta

PharmaCorp

27%

25%

1

SynerCorp

25%

32%

1.15

BioMed

23%

36%

1.3

Safemed

21%

40%

1.4

a. Calculate the degree of operating leverage for each of these firms.

b. Use the operating leverage to explain why these firms have different betas.