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%

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