Confidence Intervals for Means Warm Up Mar 22

A quality control specialist at a glass factory must estimate the mean clarity rating for a new batch of glass using a sample of 18 glass sheets from the batch. Past investigations show that clarity ratings are normally distributed. The specialist decides to use a t-distribution rather than a z-distribution because ...

• The t distribution is more accurate than a z distribution.

• Clarity ratings for the entire bacth are normally distributed.

• The t-distribution will create a narrower interval than z.

• The standard deviation for the population is unknown.

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

Which of the following changes to a study would result in a narrower confidence interval?

• increasing the confidence level, increasing the sample size
• decreasing the confidence level, decreasing the sample size
• increasing the confidence level, decreasing the sample size
• decreasing the confidence level, increasing the sample size.

Tags

CCSS.HSS.IC.B.4

Which of the following does NOT have an affect on the margin of error of a confidence interval?

• Sample mean

• t*

• Sample standard deviation

• Sample size

Tags

CCSS.HSS.IC.B.4

A 90% confidence interval for the mean speed driven by cars on Due West Road is given by (21, 45). What was the sample mean of this study?

• 12

• 24

• 33

• None of these.

Tags

CCSS.HSS.IC.B.4

A 90% confidence interval for the mean speed driven by cars on Due West Road is given by (21, 45). What was the margin of error of this interval?

• 12

• 24

• 33

• None of these.

Tags

CCSS.HSS.IC.B.4

Find the t* value for a 99% confidence interval with a sample of 23 people.

• 1.714
• 1.711
• 2.064
• None of these.

What is the t value associated with 90% confidence and a sample size of 15?

• 1.341
• 1.345
• 1.761
• 1.753

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

How do you calculate degrees of freedom?

• n

• n+1

• 1-n

• n-1

An IQ test was given to a 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.

What is the point estimate?

• 75

• 105.2

• 10

• 0.90

Tags

CCSS.HSS.IC.B.4

If the 95% Confidence Interval for a population mean is (114.56, 125.54), then is it likely that the true population mean µ is greater than 130?

• Yes

• No

• Not enough information

• I have no idea what you're asking of me

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1