Ch 7 test review

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.

What is the point estimate?

• 75

• 105.2

• 10

• 0.90

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

• 1.90

• 75

• 0.90

• 105.2

The lifetime of a certain type of batter is known to be normally distributed with a standard deviation of 20 hours. A sample of 60 batteries had a mean lifetime of 120.1 hours.

What is the formula for the 99% confidence interval?

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True or False:

The more confident you want to be, the smaller your confidence interval will be.

• True

• False

What is the effect of increasing sample size?

• increases margin of error and makes the interval wider

• decreases margin of error and makes the interval narrower

• increases margin of error and makes the interval narrower

• decreases margin of error and makes the interval wider

When constructing a confidence interval for a proportion, we want to make sure our sample data and sample statistics are unbiased. The best way to ensure this is to:

• randomly select the sample

• ask a large number of people: n>30

• Ask less than 10% of the population: n<10%(Population)

A 95% confidence interval for the proportion of people who feel closer to their immediate family as a result of the shelter in place is (.44, .54). Does the interval provide convincing evidence that more than half of people now feel closer to their family?

• Yes, because .50 is contained in the interval and is a plausible value.

• No, because the middle of the interval is actually .49, which is less than half.

• No, because the interval has a margin of error, and so we think the interval is not correct.

• No because the interval is not entirely above .50. Some of the plausible values are less than 50%.

What critical value do we use when testing claims about population means?

• x-bar

• z*

• t*

• p-hat

What critical value do we use when testing claims about population proportion?

• x-bar

• z*

• t*

• p-hat

A study found that in a sample of 44 subjects, 9 of agree that children under 6 shouldn’t be taken to nice restaurants.

The 95% confidence interval for p is (0.082, 0.318). Interpret this interval.

• 95% of the time the proportion of people who believe children under 6 shouldn't be taken to nice restaurants will be between 8.2% and 31.8%.

• The population proportion of people who believe children under 6 shouldn't be taken to nice restaurants is between 8.2% and 31.8%.

• The probability that the proportion of people who believe children under 6 shouldn't be taken to nice restaurants will be between 8.2% and 31.8% is 95%.

• Based on this sample, I am 95% confident that the proportion of people who believe children under 6 shouldn't be taken to nice restaurants is between 8.2% and 31.8%.