The Cairo Center for Rural Studies estimates that about 6% of Egypt’s citizens do not have adequate access to drinking water.  Suppose, as part your research there, you determine that the amount of rainfall annually in Egypt is a continuous random variable distributed normally with an average amount of rainfall of 6 inches with a standard deviation of 1.10 inches.  Can you help government officials there determine what level of annual rainfall has 2.3% below it?

Students preparing for comprehensive exams usually spend many hours studying. Suppose it is known that the time students spend studying for comprehensive exams has a distribution that is skewed heavily to the right with a mean of 41.3 hours and a standard deviation of 6.8 hours. If a simple random sample of 72 students is selected and the amount of time each spent studying for the comprehensive exam is determined. State and check the two assumptions.

Based on data from the National Health Board, weights of men are normally distributed with a mean of 178 lbs, and a standard deviation of 29 lbs. Find the probability that 20 randomly selected men will have a mean weight between 170 and 190.

A certain prescription medicine is supposed to contain an average of 250 parts per million (ppm) of a certain chemical. If the concentration is higher than this, the drug may cause harmful side effects; if it is lower, the drug may be ineffective. The manufacturer runs a check to see if the mean concentration in a large shipment conforms to the target level of 250 ppm or not. A simple random sample of 100 portions is tested, and the sample mean concentration is found to be 247 ppm. The sample concentration standard deviation is s = 12 ppm. What are the appropriate null and alternative hypotheses? Group of answer choices H 0:  x̄ = 250 vs. H a:  x̄ < 250 H 0:  x̄ = 250 vs. H a:  x̄ ≠ 250 H 0:  x̄ = 250 vs. H a:  x̄ > 250 H 0: μ = 250 vs. H a:μ < 250 H 0: μ = 250 vs. H a: μ ≠ 250 H 0: μ = 250 vs. H a: μ > 250

One year, the distribution of salaries for professional sports players had a mean of $1.6 million and a standard deviation of $0.7 million. Suppose a sample of 100 major league players was taken. Find the approximate probability that the average salary of the 100 players that year exceeds $1.1 million.

Fuel efficiency of Prius:  Fueleconomy.gov, the official US government source for fuel economy information, allows users to share gas mileage information on their vehicles. The histogram below shows the distribution of gas mileage in miles per gallon (MPG) from 14 users who drive a 2012 Toyota Prius. The sample mean is 53.3 MPG and the standard deviation is 5.2 MPG. Note that these data are user estimates and since the source data cannot be verified, the accuracy of these estimates are not guaranteed. (a) The EPA claims that a 2012 Prius gets 50 MPG (city and highway mileage combined). Do these data provide strong evidence against this estimate for drivers who participate on fueleconomy.gov? The test statistic is: __________________(please round to two decimal places)The p-value:___________________________ for this hypothesis test is:  (please round to four decimal places)(c) Please comment on the primary thing that is wrong about the following statement: There is sufficient evidence…

A report about how American college students manage their finances includes data from a survey of college students. Each person in a representative sample of 793 college students was asked if they had one or more credit cards and if so, whether they paid their balance in full each month. There were 500 who paid in full each month. For this sample of 500 students, the sample mean credit card balance was reported to be $825. The sample standard deviation of the credit card balances for these 500 students was not reported, but for purposes of this exercise, suppose that it was $205. Is there convincing evidence that college students who pay their credit card balance in full each month have a mean balance that is lower than $907, the value reported for all college students with credit cards? Carry out a hypothesis test using a significance level of 0.01.   State the appropriate null and alternative hypotheses. H0: ? = 907 Ha: ? < 907 H0: ? = 907 Ha: ? > 907      H0: ? < 907…

A study shows that Michigan teachers have measures of job dissatisfaction that are normally distributed with a mean of 3.80 and standard deviation of 0.95. If subjects with scores above 4.0 are to be given more tests, what percentage will fall into that category?

Suppose a researcher pbserves a population of 12 people and computes SS=204. What is the variance? What is the standard deviation?