Questions from Statistics Principles

Q: Find the standardized variable Z if X has (a)

Find the standardized variable Z if X has (a) Mean 13 and standard deviation 3. (b) Mean 57 and standard deviation 16. (c) Mean 142 and variance 36.

Q: A researcher wants to estimate µ, the mean number of minutes

A researcher wants to estimate µ, the mean number of minutes before a person scores over 200 on a new computer game. She wishes to get estimates, separately, for each of the groups (a) novices, (b) oc...

Q: Referring to Exercise 8.4, suppose that the survey of

Referring to Exercise 8.4, suppose that the survey of 50 contested items was, in fact, a pilot study intended to give an idea of the population standard deviation. Assuming ( = $25, determine the samp...

Q: To estimate µ with a 90% error margin of 2.

To estimate µ with a 90% error margin of 2.9 units, one has determined that the required sample size is 108. What then is the required sample size if one wants the 95% error margin to be 1.8 units?

Q: Table records the number of items returned by 30 persons to a

Table records the number of items returned by 30 persons to a large discount department store in late December. The summary statistics are n = 30, x = 2.538, s = 1.303 Obtain a 98% confidence interv...

Q: A company wants to check the consistency of electronic copies of signatures

A company wants to check the consistency of electronic copies of signatures for consumer credit purchases. A sample of 49 electronic signatures are available from the same customer. One measure of con...

Q: Each day of the year, a large sample of cellular phone

Each day of the year, a large sample of cellular phone calls is selected and a 95% confidence interval is calculated for the mean length of all cellular phone calls on that day. Of these 365 confidenc...

Q: A nutritionist records the time to eat an evening meal, at

A nutritionist records the time to eat an evening meal, at a student cafeteria, for 64 students. She obtains x = 36.2 and s = 5.6 minutes and reports that the 95% confidence interval for the mean time...

Q: In a study on the nutritional qualities of fast foods, the

In a study on the nutritional qualities of fast foods, the amount of fat was measured for a random sample of 35 hamburgers of a p articular restaurant chain. The sample mean and standard deviation wer...

Q: In a study designed to find differences in personality between cat and

In a study designed to find differences in personality between cat and dog lovers, 3 subjects were first classified according to their answers to a questionnaire about attitudes towards pets, and prev...