When σ is unknown and the sample is of size

Annette Arroyo
2021-05-08
Answered

When σ is unknown and the sample is of size

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BleabyinfibiaG

Answered 2021-05-09
Author has **118** answers

90%: 43.6341 to 46.7659

95%: 43.3343 to 47.0657

99%: 42.7441 to 47.6559

95%: 43.3343 to 47.0657

99%: 42.7441 to 47.6559

asked 2021-08-03

A simple random sample of 60 items resulted in a sample mean of 80. The population standard deviation is $\sigma =15$

a) Compute the$95\mathrm{\%}$ confidence interval for the population mean. Round your answers to one decimal place.

b) Assume that the same sample mean was obtained from a sample of 120 items. Provide a$95\mathrm{\%}$ confidence interval for the population mean. Round your answers to two decimal places.

c) What is the effect of a larger sample size on the interval estimate?

Larger sample provides a-Select your answer-largersmallerItem 5 margin of error.

a) Compute the

b) Assume that the same sample mean was obtained from a sample of 120 items. Provide a

c) What is the effect of a larger sample size on the interval estimate?

Larger sample provides a-Select your answer-largersmallerItem 5 margin of error.

asked 2021-03-09

In a study of the accuracy of fast food drive-through orders, Restaurant A had 298 accurate orders and 51 that were not accurate. a. Construct a 90% confidence interval estimate of the percentage of orders that are not accurate. b. Compare the results from part (a) to this 90% confidence interval for the percentage of orders that are not accurate at Restaurant B:

asked 2021-08-09

A clinical trial was conducted to test the effectiveness of a drug for treating insomnia in older subjects. Before treatment, 13 subjects had a mean wake time of 101.0 min. After treatment, the 13 subjects had a mean wake time of 94.6 min and a standard deviation of 24.9 min. Assume that the 13 sample values appear to be from a normally distributed population and construct a

Construct the

What does the result suggest about the mean wake time of 101.0 min before the treatment? Does the drug appear to be effective?

The confidence interval ▼ does not include| includes the mean wake time of 101.0 min before the treatment, so the means before and after the treatment ▼ could be the same |are different. This result suggests that the drug treatment ▼ does not have | has a significant effect.

asked 2021-02-23

Suppose that a random sample of 50 bottles of a particular brand of cough syrup is selected and the alcohol content of each bottle is determined. Let j: denote the average alcohol content for the population of all bottles of the brand under study. Suppose that the resulting 95% confidence intervals (7-8, 9.6)

(a) Would 2 90%% confidence interval calculated from this same sample have been narrower or wider than the glven interval? Explain your reasoning.

(b) Consider the following statement: There is 9 95% chance that Is between 7.8 and 9.6. Is this statement correct? Why or why not?

(c) Consider the following statement: We can be highly confident that 95% of al bottles ofthis type of cough syrup have an alcohol content that is between 7.8 and 9.6. Is this statement correct? Why or why not?

(a) Would 2 90%% confidence interval calculated from this same sample have been narrower or wider than the glven interval? Explain your reasoning.

(b) Consider the following statement: There is 9 95% chance that Is between 7.8 and 9.6. Is this statement correct? Why or why not?

(c) Consider the following statement: We can be highly confident that 95% of al bottles ofthis type of cough syrup have an alcohol content that is between 7.8 and 9.6. Is this statement correct? Why or why not?

asked 2022-03-25

Confidence in sample mean, given sample variance?

Let's say that I have an large population of data, but that I have a sample mean and sample variance calculated from a subset of that data.

Can I use my sample variance (or standard deviation) to know how confident I should be in my sample mean being close to the population mean?

It seems like I should because a low variance seems to indicate that there isn't very far that the mean could move, but on the other hand, taking more samples isn't going to make the variance approach zero.

Is there some other calculation I should be using for getting a confidence amount in my sample mean?

Let's say that I have an large population of data, but that I have a sample mean and sample variance calculated from a subset of that data.

Can I use my sample variance (or standard deviation) to know how confident I should be in my sample mean being close to the population mean?

It seems like I should because a low variance seems to indicate that there isn't very far that the mean could move, but on the other hand, taking more samples isn't going to make the variance approach zero.

Is there some other calculation I should be using for getting a confidence amount in my sample mean?

asked 2022-03-13

What sample size is necessary for 95% CI?

A state legislator wishes to survey residents of her district to see what proportion of the electorate is aware of her position on using state funds to pay for abortions.

a. What sample size is necessary if the 95% CI for p is to have a width of at most 0.10 irrespective of p?

b. If the legislator has strong reason to believe that at least$\frac{2}{3}$ of the electorate know of her position, how large a sample size would you recommend?

A state legislator wishes to survey residents of her district to see what proportion of the electorate is aware of her position on using state funds to pay for abortions.

a. What sample size is necessary if the 95% CI for p is to have a width of at most 0.10 irrespective of p?

b. If the legislator has strong reason to believe that at least

asked 2021-08-06

Out of a 54 person sample from our fall Math-150 classes, $12.4\mathrm{\%}$ of the students are left-handed. Using a TI 84 graphing calculator:

Construct an$80\mathrm{\%}$ confidence interval for the population proportion, p. Round to tenths of a percent and write a sentence answer.

The U.S. has$13.1\mathrm{\%}$ of it’s population that are left-handed. Did this fall in your confidence interval from part a?

Be sure to show all calculator commans used.

Construct an

The U.S. has

Be sure to show all calculator commans used.