A municipal bond service has three rating categories (A, B, and C). Suppose that in the past year, of the municipal bonds issued in the United States, 60% were rated A, 25% were rated B, and 15% were rated C. Of the municipal bonds rated A, 50% were issued by cities, 30% by suburbs, and 20% by rural areas. Of the municipal bonds rated B, 40% were issued by cities, 35% by suburbs, and 25% by rural areas. Of the municipal bonds rated C, 80% were issued by cities, 15% by suburbs, and 5% by rural areas. Suppose there are a total of 100,000 bonds.
1. What proportion of municipal bonds are issued by suburbs?
2. What proportion are issued by suburbs and are rated B?
3. What proportion are issued by suburbs or rated B
4. If a municipal bond is to be issued by a suburb, what is the probability that it will receive a B rating?
5. Are “Issued by Suburb” and “B rated independent?