Suppose a random sample of 49 is selected from a population with a
(outside or inside) the confidence interval. Therefore, there is no reason to reject the Runzheimer figure as different from what we are getting based on this sample.
According to a survey by Runzheimer International, the average cost of a fast-food meal (quarter-pound cheeseburger, large fries, medium soft drink, excluding taxes) in Seattle is $4.82. Suppose this figure was based on a sample of 27 different establishments and the standard deviation was $0.37. Construct a 95% confidence interval for the population mean cost for all fast-food meals in Seattle. Assume the costs of a fast-food meal in Seattle are normally distributed. Using the interval as a guide, is it likely that the population mean is really $4.50? Why or why not?
Round the answers to 4 decimal places.
in the interval, we are 95% confident that μ
4.50.
The tolerance is +/- 0.0005.
Assuming x is normally distributed, use the following information to compute a 90% confidence interval to estimate .
|
313 |
320 |
319 |
340 |
325 |
310 |
|
321 |
329 |
317 |
311 |
307 |
318 |
Round the answers to 2 decimal places.
[removed] ≤ μ ≤
[removed]
The tolerance is +/- 0.05.
|
|
The marketing director of a large department store wants to estimate the average number of customers who enter the store every five minutes. She randomly selects five-minute intervals and counts the number of arrivals at the store. She obtains the figures 54, 32, 41, 44, 56, 80, 49, 29, 32, and 74. The analyst assumes the number of arrivals is normally distributed. Using these data, the analyst computes a 95% confidence interval to estimate the mean value for all five-minute intervals. What interval values does she get?
Round the intermediate values to 2 decimal places. Round your answers to 2 decimal places, the tolerance is +/-0.01.
[removed] ≤ μ ≤
[removed]
A meat-processing company in the Midwest produces and markets a package of eight small sausage sandwiches. The product is nationally distributed, and the company is interested in knowing the average retail price charged for this item in stores across the country. The company cannot justify a national census to generate this information. Based on the company information system’s list of all retailers who carry the product, a researcher for the company contacts 36 of these retailers and ascertains the selling prices for the product. Use the following price data and a population standard deviation of 0.113 to determine a point estimate for the national retail price of the product. Construct a 90% confidence interval to estimate this price.
|
$2.23 |
$2.11 |
$2.12 |
$2.20 |
$2.17 |
$2.10 |
|
2.16 |
2.31 |
1.98 |
2.17 |
2.14 |
1.82 |
|
2.12 |
2.07 |
2.17 |
2.30 |
2.29 |
2.19 |
|
2.01 |
2.24 |
2.18 |
2.18 |
2.32 |
2.02 |
|
1.99 |
1.87 |
2.09 |
2.22 |
2.15 |
2.19 |
|
2.23 |
2.10 |
2.08 |
2.05 |
2.16 |
2.26 |
Round the answers to 3 decimal places.
[removed]Point Estimate
[removed] ≤ μ ≤
[removed]
The tolerance is +/- 0.005.
A bank officer wants to determine the amount of the average total monthly deposits per customer at the bank. He believes an estimate of this average amount using a confidence interval is sufficient. How large a sample should he take to be within $200 the actual average with 99% confidence? He assumes the standard deviation of total monthly deposits for all customers is about $1,000.
Round your answer up to the nearest integer.
The tolerance is +/- 1.
Suppose you have been following a particular airline stock for many years. You are interested in determining the average daily price of this stock in a 10-year period and you have access to the stock reports for these years. However, you do not want to average all the daily prices over 10 years because there are several thousand data points, so you decide to take a random sample of the daily prices and estimate the average. You want to be 90% confident of your results, you want the estimate to be within $3.00 of the true average, and you believe the standard deviation of the price of this stock is about $12.75 over this period of time. How large a sample should you take?
Sample size = [removed]
A national beauty salon chain wants to estimate the number of times per year a woman has her hair done at a beauty salon if she uses one at least once a year. The chain’s researcher estimates that, of those women who use a beauty salon at least once a year, the standard deviation of number of times of usage is approximately 6. The national chain wants the estimate to be within one time of the actual mean value. How large a sample should the researcher take to obtain a 98% confidence level?
Round your answer up to the nearest integer.
Sample [removed].
The tolerance is +/- 1.
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