Chap 7 # 15
Retail stores experience their heaviest returns on December 26 and December 27 each year. Most are gifts that, for some reason, did not please the recipient. The number of items returned, by a sample of 30 persons at a large discount department store, are observed and the summary statistics below are obtained.
n=30 x =2.468 s = 1.207
NOTE: The X has a line over it.
Determine a 98% confidence interval for the population mean number of items returned.
Confidence interval = ( , )
Stated here are some claims or research hypotheses that are to be substantiated by sample data.
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Chap 8# 21
Identify the null hypothesis and the alternative hypothesis in terms of the population mean The mean time a health insurance company takes to pay claims is less than 20 working days.
NOTE: the first H has a 0 next to it; the second H has a 1 next to it.
Chap 9 # 10
Recorded here are the germination times (number of days) for seven seeds of a new strain of snap bean.
12 16 15 49 17 11 18
Determine a 95% confidence interval for the true mean germination time for this strain. Assume that measurements are normally distributed.
Round to two decimal places.
(, ) days; answers are incorrect
Chap 7 #13b
A population has mean 73 and standard deviation 14. Calculate for a random sample of size 16 23.4 (Round to one decimal place.)
Chap 7, #16c
A population has standard deviation 24. What is the standard deviation of for a random sample of size n=144 70 (Round to one decimal place) (incorrect answer shown)
Note: X has a line over it
Chapter 2, Section 2.3, Problem 51b
| Incorrect. | |
The city of Madison regularly checks the water quality at swimming beaches located on area lakes. The concentration of fecal coliforms, in number of colony forming units (CFU) per 100 ml of water, was measured on fifteen days during the summer at one beach.
With reference to the given data, find the sample 90th percentile.
360
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