A national standard requires that public bridges over 20 feet in length must be inspected and rated every 2 years. The rating scale ranges from 0...

A national standard requires that public bridges over 20 feet in length must be inspected and rated every 2 years. The rating scale ranges from 0 (poorest rating) to 9 (highest rating). A group of engineers used a probabalistic model to forecast the inspection ratings of all major bridges in a city. For the year 2020, the engineers forecast that 10% of all major bridges in that city will have ratings of 4 or below. Complete parts a and b, showing work.

A. Use the forecast to find the probability that in a random sample of 11 major bridges in the city, at least 3 will have an inspection rating of 4 or below in 2020.

B. Suppose that you actually observe 3 or more of the sample of 11 bridges with inspection ratings of 4 or below in 2020. What inference can you make? Why?