Confidence Intervals 낱말 카드 | Quizlet

When do you use t*?

Means when you don't know the population standard deviation.

When do you use z*?

Means when you know the population standard deviation and proportions.

What's the formula for a one sample proportion confidence interval?

What's the formula for a one sample mean confidence interval?

What are 3 ways to reduce margin of error?

1. Increase sample size (n)

2. Use a lower level of confidence

3. Reduce σ

What statement is used to conclude a confidence interval?

I am _____ % confident that the true mean/proportion of (context) is between ______ and ______.

What conditions need to be checked for confidence intervals?

1) SRS

2) Normality

3) Independence

How do you interpret a confidence level?

If you took all possible samples of size n, the true parameter would fall in about ____% of them.

A poll is to be conducted to estimate what proportion of people that work indoors smoke. The researchers want to be 90% confident that this proportion is within 3.5% of the true value. Of the following, which is the smallest sample size that will satisfy the manufacturer's requirements?

550

Which of the following values below represents the critical value for a 98% confidence interval for proportions?

2.326

Which of the following is the critical value for an 80% confidence interval for proportions?

1.282

The 99% confidence interval for a proportion is (0.54, 0.72). What was the sample proportion used to create this interval?

0.63

Which z-value is used for a 95% confidence interval?

1.96

What is the degrees of freedom equal to?

n-1

You take a poll and find that 34% of the 100 people you asked dislike school lunches. Using a 95% confidence level, what is the margin of error?

0.093

The 99% confidence interval for a proportion is (0.54, 0.72). What the margin of error for this interval?

0.09

The 99% confidence interval for a proportion is (0.54, 0.72). What is p̂?

0.63

The 99% confidence interval for a proportion is (0.52, 0.72). What is the margin of error?

0.1

A nurse at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 95% confident that the true mean is within 3 ounces of the sample mean? The standard deviation of the birth weights is known to be 6 ounces.

16

The standard IQ test has a mean of 96 and a standard deviation of 14. We want to be 99% certain that we are within 4 IQ points of the true mean. Determine the required sample size.

82

A sample size of n = 64 is drawn from a population whose standard deviation is σ = 5.6.

Find the margin of error for a 99% confidence interval for µ.

1.803

An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college.

What is the point estimate?

105

An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105.2. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college.

1.67

An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105.2. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college.

Find the Standard Error.

1.155

An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105.2. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college.

Find the Margin of Error

1.9