What is the main difference between problem $1$ and problem $2?$Fall $2024$ Al Yamamah UniversityProblem $4$: A municipal bond service has three rating categories $($A$,$ B$,$ and C$).$ Suppose that in the past year, of the municipal bonds issued throughout the United States, $70\%$ were rated A$,20\%$ were rated B$,$ and $10\%$ were rated C$.$ Of the municipal bonds rated A$,50\%$ were issued by cities, $40\%$ by suburbs, and $10\%$ by rural areas. Of the municipal bonds rated B$,60\%$ were issued by cities, $20\%$ by suburbs, and $20\%$ by rural areas. Of the municipal bonds rated C$,90\%$ were issued by cities, $5\%$ by suburbs, and $5\%$ by rural areas.a$.$ If a new municipal bond is to be issued by a city, what is the probability that it will receive an A rating?b$.$ What proportion of municipal bonds are issued by cities?c$.$ What proportion of municipal bonds are issued by suburbs?