Total industry sales are $100 billion. The four largest firms have sales of $35 billion, $17 billion, $6.8 billion, and $2.2 billion. The industry's approximate four-firm concentration ratio is

The industry's approximate four-firm concentration ratio is 61%

Explanation:

Hi, to answer this question, first we have to sum all the four firms sales:

Mathematically speaking:

35 + 17 + 6.8 + 2.2 = 61 billion

Now, we have to divide the result by the total industrial sales:

61 billion /100 billion = 0.61

To express it as a percentage we have to multiply it by 100

0.61 x 100 = 61%

The industry's approximate four-firm concentration ratio is 61%

Feel free to ask for more if needed or if you did not understand something.  

answer; buying the bill at a discount from the face value to be received at maturity;

answerjointly by the fed and by the behavior of individuals who hold money and of banks in which money is held;