Three Companies Share the Entire Market for a Particular Product $50 \%$

Short Answer

Three companies share the entire market for a particular product. Company A has a $50 \%$ share, company B has a $\mathbf{3 0} \%$ } share, and company $\mathrm{C}$ has a $20 \%$ .
-If 12 people who buy the product are selected at random, find the probability that five buy the product from company A, four from company B, and three from company C.