Suppose that new razor blades were introduced in the market by three companies at the same time. When they were introduced, each company had an equal share in the market, but during the first year the following changes took place:

(i) Company A retained 90 per cent of its customers, lost 3 per cent to B and 7 per cent to C.

(ii) Company B retained 70 per cent of its customers, lost 10 per cent to A, and 20 per cent to C.

(iii) Company C retained 80 per cent of its customers, lost 10 per cent to A, and 10 per cent to B.

Assuming that no changes in the buying habits of the consumer occur.

(a) What are the market shares of the three companies at the end of the first year? The second year?

(b) What are long-run market shares of the three companies?