Confidence Intervals for Large Means Intro

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

CCSS.HSS.IC.A.1

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

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

• 2.58

• 1.66

• 1.96

• 2.33

The amount added and subtracted to the statistic.

• Margin of Error

• Confidence Interval

• Z Score

• Population

Identify the confidence interval used in the figure below if each shaded area is equal to 0.05.

• 90%

• 95%

• 97%

• 99%

A sample of 30 women finds the mean height 62.3 in and the standard deviation 1.5 in. Find the margin of error of women's heights with a 95% CL. Round your critical value to 3 decimals.

• 1.699
• 0.56
• 0.537
• 19.325

In a crash test of 55 troopers, collision repair costs were found to have an approximately normal distribution, with a mean of $1800 and a standard deviation of $950. Using the formula, construct a 99% confidence interval for the repair cost. Round your critical value to 3 decimals and your interval to 2 decimals.

• (1470.02, 2129.98)

• (1373.65, 2326.69)

• (1799.02, 1801.54)

• None of these.

What is the critical value (z-score) for a 99% confidence interval? Round to 3 decimals.

• 2.326

• 1.96
• 1.645

• 2.576

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

The lifetime of a certain type of battery 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. It is desired to construct a 99% confidence interval for the mean lifetime of this type of battery.

Using your calculator, what is the Confidence Interval to one decimal place?

• (114.5, 125.6)

• (112.8, 127.4)

• (112.82, 127.38)

• (114.56, 125.64)