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A multiple regression line was calculated in which x1 was a student's grade point average and x2 was a student's age. The multiple regression line was calculated as y' = -18.7 + 46.3 x1 + 7.28 x2. I
Compute the standard error of the estimate for the data below. X values 56 68 78 85 98 Y values 87 110 138 161 186
If in an observational study the statistical analysis has shown convincing evidence that the mean levels differed in two groups (treatment and control groups), can one conclude that the treatment wa
Answer the following questions by checking either True or False. All other factors remaining the same, a 90% confidence interval is more narrow than a 95% confidence interval.
Test the significance of the correlation coefficient r at a = 0.05 for the data below.
Assume that you have a box with an equal number of $4, $6, $8 chips. a. Find the population mean and the standard deviation.
A marketing firm asked a random set of married and single men as to how much they were willing to spend for a vacation. At alpha= .05, is a difference in the two amounts?
At the .05 level of significance, is there sufficient evidence to conclude that a difference exists between the proportion of students who have ear infections at one school and the other?
Assume further that this sum may be considered to be the sum of an independent trials process with 100 experiments each having expected value of 10 pounds and standard deviation 1. Find the approxim
What is the critical value for a two-tailed F -test with alpha=0.10 , when the sample size from which the c was 10, and the sample size from which the denominator was obtained was 24?
The number of times a batter gets to bat in a game follows a binomial distribution N~BIN(6, 0.8). Given the number of times at bat, n, that the batter has, the number of hits he gets conditionally f
Two t-shirt printing factories produce t-shirts for a local sports team. Factory A produces 60% of the shirts and factory B produces 40%. Five percent of the shirts from Factory A are defective, and
Assume that in a hypothesis test with null hypothesis Ho:u = 12.0 at alpha= 0.05, that a value of 10.0 for the sample mean results in the null hypothesis to be not rejected. That corresponds to a co
A college believes that 24% of applicants to that school have parents who have remarried. How large a sample is needed to estimate the true proportion of students who have parents who have remarried
It was found that in a sample of 90 teenage boys, 70% of them have received speeding tickets. What is the 90% confidence interval of the true proportion of teenage boys who have received speeding ti
A researcher conducted a study of the access speed of 45 hard drives and concluded that his maximum error of estimate was 18. If he were to conduct a second study to reduce the maximum error of esti
A random sample of 70 voters found that 40% were going to vote for a certain candidate. Find the 99% limit for the population proportion of voters who will vote for that candidate.
A random sample of 30 students results in a sample mean age of 20 years with a sample standard deviation of 1.5 years. Assume age is normally distributed. To test the hypothesis H0: ? = 21, we would
Suppose the claimed drying time is true, that is ? = 45 minutes, what is the probability of observing a sample mean of x = 52 or greater from a sample size of 25? (Round your answer to four decimal
The resulting "life" data from the batteries had a mean of 22.5 hours. Assume these values have a normal distribution with a standard deviation of 1.58 hours.
A random sample of 70 needles was taken from a medical manufacturing facility and 24 were found to be defective. Calculate a 99% confidence interval for the true proportion of defective needles.
The wall thickness of 20 glass 2-liter bottles was measured by a quality control engineer. The sample mean was Xbar=4.05 millimeters, and the sample standard deviation S=0.08 millimeters. Computer a
The standard deviation of the lifetime of a sample of 15 electric light bulbs was computed to be 98 hours and the lifetime duration follows a normal distribution. Find a 95% CI for the standard devi
A random sample has been taken from a normal distribution and the following confidence intervals were constructed using the same data: