Consider an industry whose firms have the following sales:

Firm Sales Firm Sales
Appel 1000 Fettucini 200
Banana 800 Grapefruit 150
Cumquat 600 Hamburger 100
Dellta 400 InstantCoffee 50
Endive 300 Jasmine 1
The Herfindahl-Hirschman Index (HHI) is defined as
HHI=(market share of firm 1 in %)^2
+(market share of firm 2 in %)^2+
+(market share of last firm in %)^2
a. Calculate the four-firm and six-firm concentration ratios for the computer industry.
b. Calculate the HHI for the industry.
c. Suppose that Appel Computer and Banana Computer were to merge with no change in the sales of any of the different computers. Calculate the new HHI.