Stats quiz

20 questions for XXIAO onlyhere is my quiz one attached and a copy on here.Question 1 of 201.0 PointsAccepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e.g., as thousands separator, 5 000), “E” or “e” (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values.For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.A sample of 9 production managers with over 15 years of experience has an average salary of $71,000 and a sample standard deviation of $18,000.Assuming that the salaries of production managers with over 15 years experience are normally distributed, you can be 95% confident that the mean salary for all production managers with at least 15 years of experience is between what two numbers.Place your LOWER limit, rounded to a whole number, in the first blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 54321 would be a legitimate entry.Reset SelectionQuestion 9 of 201.0 PointsFrom a sample of 500 items, 30 were found to be defective. The point estimate of the population proportion defective will be:Reset SelectionQuestion 10 of 201.0 PointsFind the 95% confidence interval for the standard deviation of the lengths of pipes if a sample of 26 pipes has a standard deviation of 10 inches.Reset SelectionQuestion 11 of 201.0 PointsCompute    where t20 has a t-distribution with 20 degrees of freedom.Reset SelectionQuestion 12 of 201.0 PointsWhich of the following will make a confidence interval narrower and more precise?Reset SelectionQuestion 13 of 201.0 PointsA sample of 23 European countries found that the variance of life expectancy was 7.3 years. What is the 95% confidence interval estimate for the variance of life expectancy in Europe?Reset SelectionQuestion 14 of 201.0 PointsThe t- distribution for developing a confidence interval for a mean has _____ degrees of freedom.Reset SelectionQuestion 15 of 201.0 PointsIf you are constructing a confidence interval for a single mean, the confidence interval will___________ with an increase in the sample size.Reset SelectionQuestion 16 of 201.0 PointsConfidence intervals are a function of which of the following three things?Reset SelectionQuestion 17 of 201.0 PointsIf you increase the confidence level, the confidence interval ____________.Reset SelectionQuestion 18 of 201.0 PointsThe average gas mileage of a certain model car is 26 miles per gallon. If the gas mileages are normally distributed with a standard deviation of 1.3, find the probability that a randomly selected car of this model has a gas mileage between 25.8 and 26.3 miles per gallon.Reset Selection