3) In a New York modeling agency, a researcher wishes to see if the average height of female models is really less than 67 inches, as the chief claims. A random sample of 20 models has an average height of 65.8 inches. The standard deviation of the sample is 1.7 inches. At α = 0.05, is the average height of the models really less than 67 inches? Assume that the population is normally distributed. Required steps: 1) label all given information 2) state the null and alternative hypothesis and identify the claim
 3) verify that the conditions are met to perform the test 4) sketch the normal distribution (curve) and find the critical regions
 5) compute the test statistic
 6) make a decision to reject or not reject the null hypothesis 
7) summarize the results in a statement

According to United States Department of Agriculture, the average retail price of conventional whole milk at New York City in the year 2020 (up to November 2020 considered) is $3.92 per gallon. The standard deviation in the retail prices in the year 2020 (up to November 2020 considered) is $0.084. You are given a task of selecting randomly a sample of 85 milk bottles (whole milk of 1 gallon volume). a. Calculate µx̅ and σx̅. b. What is the approximate probability that the sample has a mean retail price that exceeds $4.05? c. What is the approximate probability that the sample has a mean retail price between $3.91 and $3.94?

A sample of 314 patients between 38 and 82 were given a drug intended to reduce their level of cholesterol. The results were the mean reduction in cholesterol of 0.94 millimole per liter. Assume the population standard deviation is σ = 0.18. Construct a 98% C.I.

A boat capsized and sank in a lake. Based on an assumption of a mean weight of 133 Ib, the boat was rated to carry 70 passengers (so the load limit was 9,310 Ib). After the boat sank, the assumed mean weight for similar boats was changed from 133 lb to 174 lb. Complete parts a and b below. a. Assume that a similar boat is loaded with 70 passengers, and assume that the weights of people are normally distributed with mean of 181.1 Ib and a standard deviation of 38.6 lb. Find the probability that the boat is overloaded because the 70 passengers have mean weight greater than 133 lb The probability isO: (Round to four decimal places as needed.) b. The boat was later rated to carry only 17 passengers, and the load limit was changed to 2,958 Ib. Find the probability that the boat is overloaded because the mean weight of the passengers is greater than 174 (so that their total weight is greater than the maximum capacity of 2,958 Ib). The probability is. (Round to four decimal places as needed.)…