N industry consists of three firms with sales of $360,000, $650,000, and $265,000.

a. calculate the herfindahl-hirschman index (hhi)

These three together form total market, so here we have to add up everything to know volume of the market

A+B+C = 1,275,000 is the total market

Then we have to calculate individual market share

which would eb 1) 28.2%, 2) 50.9%, 3) 20.8%

This can be calcualated by simple percetage calculation. (1275000-360000/1275000*100) - 100 will give what share each has.

Then we apply HHI formula

HHI = s1^2 + s2^2 + s3^2 + ... + sn^2

HHi is nothing but squaring of each of the percentages and adding them up

(28.2) 2 + (50.9) 2 + (20.8) 2

812+2590+432 = 3834

HHI of 3834 shows it is highly competitve market.