A department store classifies credit card customers according to the maximum amount of credit allowed per month. Preferred customers are allowed over $500 credit per month, regular customers are allowed a maximum of $500 per month, and basic customers are allowed a maximum of $50 per month. A minimum monthly charge is assessed each account. If the minimum is not paid, the account is frozen and no new charges are allowed. Past experience shows that 5% of the preferred accounts are frozen, 10%of the regular accounts are frozen, and 20% of the basic accounts are frozen each month. Suppose 20% of the accounts are preferred, 50%are regular accounts, and 30% are basic accounts. Find the probability that a particular frozen account is a preferred account.