Answer:
The answer is below
Step-by-step explanation:
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.
a. Use the forecast to find the probability that in a random sample of major bridges in the city, at least 3 will have an inspection rating of 4 or below in 2020.
Answer:
This problem is a probability binomial distribution and it can be solved using the formula:
Hence the solution to the problem is given as:
P(x ≥ 3) = 1 - P(x < 3) = 1 - [ P(x=0) + P(x=1) + P(x = 2)]
Given that p = 4% = 0.04, q = 1 - p = 1 - 0.04 = 0.96, n = 10. Hence: