A pharmaceutical company makes tranquilizers. It is assumed that the distribution for the length of time they last is approximately normal. Researchers in a hospital used the drug on a random sample of nine patients. The effectiveness periods of the tranquilizer for each patient (in hours) were as follows: 2.7, 2.8, 3.0, 2.3, 2.3, 2.2, 2.8, 2.1 and 2.4. If the error bound is 0.307, then the level of confidence interval of the mean is: None of the other options O 0.98 0.95 O 0.99

The weight of a car can influence the mileage that the car can obtain. A random sample of 17 cars was taken and the weight (in pounds) and mileage (in mpg) were recorded and are in the table below. X, weight Y, mileage 4000 23.6 4000 23.4 2500 40.9 3500 28 2750 46.9 3000 32.2 3000 31.4 4500 17.2 2250 38.9 3500 31.3 3500 32.6 2750 36.3 5500 13.2 3000 31.4 3500 31.3 2250 53.3 3500 28 a) The symbol and value of the correlation coefficient are as follows:     Round final answer to 2 decimal places.     Select an answer r R² ρ ŷ y p̂ X̄ p μ σ s  =      Interpret this value: There is a strong Select an answer positive negative  Select an answer linear quadratic bell-shaped uniform  relation between weight and mileage for cars. b) The symbol and value of the coefficient of determination are as follows:     Select an answer Fail to Reject the Null Accept the Null Reject the Null

Bottles of purified water are assumed to contain 250 milliliters of water. There is some variation from bottle to bottle because the filling machine is not perfectly precise. Usually, the distribution of the contents is approximately Normal. An inspector measures the contents of eight randomly selected bottles from one day of production. The results are 249.3, 250.2, 251.0, 248.4, 249.7, 247.3, 249.4, and 251.5 milliliters. Do these data provide convincing evidence at α = 0.05 that the mean amount of water in all the bottles filled that day differs from the target value of 250 milliliters?

Thomas wants to compare the mean concentration of carbon monoxide (CO) on residential versus commercial streets, since these differ in terms of car traffic. In each of three neighborhoods of Montréal (named A, B, and C below), he randomly chooses four locations for each type of street, for a total of 24 observations (2 street types x 3 neighborhoods x 4 locations). At each location, he measures CO concentration in the air over a period of 10 hours (8:00 AM-6:00 PM), and obtains the following data (in ppm/h). Question: Test whether or not the difference between residential and commercial streets in mean atmospheric CO concentration is the same among the three neighborhoods, and whether or not CO concentration in the air is the same, on average, for the two types of streets. Note that Neighborhood is considered a random block factor in the ANOVA. Use significant level= 0.05.