the following sample was taken from a normally distributed population: 20,27,15,2016,22 and 13. A 95% confidence interval for the population mean using this sample is?

A learn-to-type software program claims that it can improve your typing skills. To test the claim and possibly help yourself out, you and five of your friends decide to try the program and see what happens. Use the table below to construct a 99% confidence interval for the true mean change in the typing speeds for people who have completed the typing program. Let Population 1 be the typing speed before taking the program and Population 2 be the typing speed after taking the program. Round the endpoints of the interval to one decimal place, if necessary. Typing Speeds (in Words per Minute) Before After 52 47 44 42 40 46 50 43 46 34 38 50 Lower end point upper end point

A sample of 30 beams has an average strength of 1908.8 lbs. and s = 327.1. what is the 95% confidence interval of the true population mean strength?

We take a simple random sample of 16 adults and ask them how long they sleep on atypical night. The sample mean is calculated to be 7.2 hours. Suppose it is known thatthe number of hours adults sleep at night follows a normal distribution with standarddeviation 1.8 hours. An 88% confidence interval for the true mean time adults sleep atnight is

The following random sample was selected from a normal distribution: 8, 10, 7, 9, 13, 7. The formula shown here is used to calculate a 95% confidence interval for the population mean. What number of degrees of freedom should be used to find the t-value when s is used as an estimate of o?

Which type of confidence interval should you use in this situation? An economics professor randomly selected 100 millionaires in the United States. The average age of these millionaires was 54.8 years with a standard deviation of 7.9 years. What is the 95% confidence interval for the mean age of all United States millionaires?   Question 5 options:   1)  a confidence interval for the mean using a table value from the standard normal distribution.   2)  a confidence interval for the mean using a table value from the t distribution.   3)  a confidence interval for a proportion using a table value from the standard normal distribution.   4)  a confidence interval for proportion using a table value from the t distribution.   5)  none of the above.

Suppose the method of tree ring dating gave the following dates A.D. for an archaeological excavation site. 1245 1245 1321 1191 1295 1330 1239 1250 1228 Find a 98% confidence interval for the mean of all tree ring dates from this archaeological site.

You receive a brochure from a large university. The brochure indicates that the mean class size for​ full-time faculty is fewer than 32 students. You want to test this claim. You randomly select 9 classes taught by​ full-time faculty and determine the class size of each. The results are shown in the table below 35, 28, 29, 33, 32, 40, 26, 25, 29.use a 95% confidence.

Construct a confidence interval for the mean of the paired differences for the two populations with the following information. Round the endpoints of the interval to three decimal places, if necessary. n=37n=37, d¯=2.191d¯=2.191, α=0.1α=0.1, sd=0.411sd=0.411

One hundred and twenty Americans were surveyed about how much time per month they spend watching television. The survey found a sample mean of 140 hours with a sample standard deviation of 44 hours. Construct a 99% confidence interval for the meantime spent watching television per month. Lower______hours Upper______hours