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 probabilistic model to forecast the inspection ratings of all major bridges in a city. For the year​ 2020, the engineers forecast that 4​% of all major bridges in that city will have ratings of 4 or below. Complete parts a and b.

a. Use the forecast to find the probability that in a random sample of 8 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 8 bridges with inspection ratings of 4 or below in 2020. What inference can you​ make? Why?

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