Unit 7/8 Confidence Intervals Review

Which of the following is the definition of a "point estimate?"

• The midpoint of the confidence interval

• The sample size

• The population

• The standard deviation

The amount added and subtracted to the statistic.

• Margin of error

• Statistic

• Population

• Point estimator

What is the point estimator for the interval (5 , 13)?

• 9

• 10

• 11

• 8

What is the margin of error for the interval (6, 12)?

• 3

• 9

• 6

• 8

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 T Critical Value for the mean.

• 1.67

• 1.28

• -1.67

• -1.28

The lifetime of a certain type of batter is known to be normally distributed with a standard deviation of 20 hours. A sample of 50 batteries had a mean lifetime of 120.1 hours. Construct a 99% confidence interval for the mean lifetime of this type of battery.

• (111.2, 128.9)

• (114.53, 131.23)

• (112.52, 127.68)

• (118.43, 122.43)

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?

• I have no clue

• Not enough information given

• Yes

• No

Find the Z Critical Value for an 86% Confidence Level for a proportion.

• 1.48

• -1.48

• 1.96

• -1.96

In a survey of 104 students, it was found that 79 went to the homecoming game this year.

Calculate a 99% confidence interval for a proportion.

• (.59, .79)

• (.62, .85)

• (.60, .90)

• (.65, .87)

For a sample, the 95% confidence interval is (0.20, 0.48).

What is the point estimate of this sample?

• .32

• .34

• .28

• .14