A national standard requires that public bridges over

Subject: Mathematics    / Statistics
Question
A national standard requires that public bridges over 2020 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 55%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 77major bridges in thecity, at least 3 will have an inspection rating of 4 or below in 2020.P(xgreater than or equals?3)equals=nothing(Round to five decimal places asneeded.)