Stats 6.1 / 6.2 Review (Confidence Intervals)

Find the critical value Zc that corresponds to a 98% confidence level

• 2.33

• 1.645

• 1.96

• 2.575

Tags

CCSS.HSS.ID.A.4

Find the margin of error for the given values of c, σ, and n.

c = 0.90, σ = 10.2, n = 75

• 1.06

• 1.94

• 0.22

• 1.18

Tags

CCSS.HSS.IC.B.4

In a recent study of 42 eighth graders, the mean number of hours per week that they watched television was

19.6. Assume the population standard deviation is 5.8 hours. Find the 98% confidence interval for the

population mean.

• (14.1, 23.2)

• (18.3, 20.9)

• (17.5, 21.7)

• (19.1, 20.4)

Tags

CCSS.HSS.IC.B.4

In a sample of 10 randomly selected women, it was found that their mean height was 63.4 inches. From

previous studies, it is assumed that the standard deviation σ is 2.4 and that the population of height

measurements is normally distributed. Construct the 95% confidence interval for the population mean.

• (61.9, 64.9)

• (58.1, 67.3)

• (59.7, 66.5)

• (60.8, 65.4)

Tags

CCSS.HSS.IC.B.4

Find the critical value, tc for c = 0.99 and n = 10.

• 3.169

• 3.250

• 2.262

• 1.254

Construct a 95% confidence interval for the population mean, μ. Assume the population has a normal

distribution. A sample of 20 college students had mean annual earnings of $3120 with a standard deviation of

$677.

• ($1324, $1567)

• ($2135, $2567)

• ($2803, $3437)

• ($2657, $2891)

Tags

CCSS.HSS.IC.B.4

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.

• 1.799

• 1.798

• 1.803

A sample of 20 cupcakes found the interval for average calories to be (150, 350). Which is the correct interpretation of the 95% confidence interval?

• We are 95% confident that the true mean caloric content can be found with a sample of 150 to 350 cupcakes.

• We are 95% confident that the interval (150, 350) captures the true average caloric content.

• We are 95% confident that a sample of 20 cupcakes will find 250 calories per cupcake.

• None of these are correct.

In a crash test of 15 troopers, collision repair costs are found to have a distribution that is approximately normal, with a mean of $1800 and a standard deviation of $950. Construct a 99% confidence interval for the repair cost for the population.

• (1070, 2530)

• (1273, 2326)

• (1799, 1801)

• (1776, 1823)

Complete the equation: 
point estimate +/- _____

• standard deviation
• margin of error
• critical value
• confidence level