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Does the interval calculated in part (b) contain 0? What does this tell us about whether there is a difference in the proportion?
A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed
A 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to 0.90, what is the interval for m ?
Conduct a test at alpha equal to .01 to see if there is a difference between the two different manufacturers. Consider the data to be from two different populations.
A sample of 26 elements from a normally distributed population is selected. The sample mean is 10 with a standard deviation of 4. what is the 95% confidence interval for m ?
A random sample of 36 students at a community college showed an average age of 25 years. Assume the ages of all students at the college are normally distributed with a standard deviation of 1.8 year
A random sample of 25 statistics examinations was taken. The average score in the sample was 76 with a variance of 144. Assuming the scores are normally distributed, what is the 99% confidence inte
The following data represents the running time of films produced by 2 motion picture companies. Determine the confidence interval for the difference between the means at 90% CI
What impact does this new measure of variation have on the mean number of miles driven that we also derived from our sample?
For which of the following values of p is the value of p(1 - p) maximized?
It makes no sense to find x bar for these data and use it to get a confidence interval for the mean percent μ in all 13 provinces or territories. Why not?
A random sample of 25 observations was taken from a normally distributed population. The average in the sample was 84.6 with a variance of 400. Construct a 90% confidence interval for m.
You are given the following information obtained from a random sample of 4 observations taken from a large, normally distributed population.
If you wish to estimate m correct to within 1.6, with probability equal to 0.95, how many observations should be included in your sample?
If the standard deviation of the lifetimes of vacuum cleaners is estimated to be 300 hours, how large of a sample must be taken in order to be 97% confident that the margin of error will not exceed
Find a 95% confidence interval for the difference in the mean selenium intakes for the two regions. Interpret this interval.
If past information shows a standard deviation of 7 months, what size sample should be taken so that at 95% confidence the margin of error will be 2 months or less?
In a random sample of 500 college students, 23% say that they read or watch the news every day. Develop a 90% confidence interval for the population proportion.
Six hundred consumers were asked whether they would like to purchase a domestic or a foreign automobile. Their responses are given below.
Calculate and interpret the inter-quartile range. Calculate the z-scores and state whether or not there are any outliers in this data set. Explain
A university planner wants to determine the proportion of spring semester students who will attend summer school. She surveys 32 current students discovering that 12 will return for summer school. W
A health club annually surveys its members. Last year, 33% of the members said they use the treadmill at least 4 times a week. How large of sample should be taken this year to estimate the percentag
What is the probability that Wes' poles will be correctly hung together on one hook with Andy's correctly hung together on the other hook?
Explain these results to a person who understands the t test for a single sample but knows nothing about the t test for independent means.
How large of sample should be taken this year to estimate the percentage of members who use the treadmill at least 4 times a week? The estimate is desired to have a margin of error of 5% with a 95%