Answer:
Step-by-step explanation:
To calculate concentration ratio,
CR4 = (X1 + X2 + X3 + X4) / T
In this equation:
X is the total sales of an individual company (sales figures for the four largest firms are used in the four-firm concentration ratio)
T is the total sales of the industry or market in question.
From the question, T was given as 2000, but individual sales of this companies were not given.
We have
CR4= (A+B+C+D)/2000
I believe the information provided in the question is not sufficient to determining percentage of the total output the four firms are responsible for.