Sample Mean Margin of Error

REFER TO THIS PROBLEM:   A cheese processing company wants to estimate the mean cholesterol content of all one-ounce servings of cheese. The estimate must be within 0.5 milligram of the population mean. Assume that the population standard deviation is 2.8 milligrams. What is the minimum required sample size to construct a 90% confidence interval for the population mean? ANSWER THIS QUESTION: What critical z-score value should be used?

• 1.645

• 1.96

• 2.575

• 2.8

A cheese processing company wants to estimate the mean cholesterol content of all one-ounce servings of cheese. The estimate must be within 0.5 milligram of the population mean. Assume that the population standard deviation is 2.8 milligrams. What is the minimum required sample size to construct a 90% confidence interval for the population mean? Round up your answer to the nearest whole number.

• 85

• 84

• 120

• 121

You will be conducting a study to estimate the average daily food expenditure of students. You want to be 95% confident that the sample mean will be within Php20 of the true mean. What is the margin of error?

You wish to estimate, with 99% confidence, the population proportion of employees who prefer a four-day work week. Your estimate must be accurate to within 4% of the population proportion. What is the margin of error (in decimal form)?

A study by the department of education in a certain state found that there was a mean SAT score of 534 with a margin of error of 20.

Which score(s) would fall outside the confidence interval?

• 505

• 530

• 550

• 558

A study by the department of education in a certain state found that there was a mean SAT score of 534 with a margin of error of 20.

Create a confidence interval for the true mean.

• (534, 554)

• (514, 534)

• (514, 554)

A random sample of 40 bags of Doritos was obtained. The mean weight was 15.5 oz with a standard deviation of 0.2 oz. At a 95% confidence level, find the margin of error of the sample.

The confidence interval created was between $44-$56.

What was the margin of error?

• $4

• $50

• $6

• $12

Determine whether the action would increase or decrease the margin of error:

Increase the confidence level from 95% to 99.7%

• Margin of error increases

• Margin of error decreases

Determine whether the action would increase or decrease the margin of error:

Decrease the confidence level from 95% to 68%

• Margin of error increases

• Margin of error decreases