There are 604,474 bridges in the United States. A structural engineering team randomly sample 850 bridges and categorized each as either structurally deficient (restricted to light vehicles, require immediate rehabilitation to remain open, or are closed), functionally obsolete (load carrying capacity, clearance, or approach highway alignment, or structurally sound. These three categories were recorded as 1, 2,and 3, respectively.
a. Estimate with 99% confidence the number of American bridges that are structurally deficient.
b. Estimate with 90% confidence the number of American bridges that are functionally obsolete.