Confidence interval for proportions

Alma is estimating the proportion of students in her school district who, in the past month, read at least 1 book. From a random sample of 50 students, she found that 32 students read at least 1 book last month. Assuming all conditions for inference are met, which of the following defines a 90 percent confidence interval for the proportion of all students in her district who read at least 1 book last month?

Tags

CCSS.HSS.IC.B.4

Suppose a 90 percent confidence interval to estimate a population proportion was calculated from a sample proportion of 18 percent and a margin of error of 4 percent. What is the width of the confidence interval?

• 2 percent

• 4 percent

• 8 percent

• 16 percent

• 36 percent

Tags

CCSS.HSS.IC.B.4

• There is a 0.95 probability that the proportion of all residents in the town who favor the proposal will be between 0.361 and 0.579.

• The probability that 95 percent of the residents in the town will favor the proposal is between 0.361 and 0.579.

• We are 95 percent confident that any sample of 83 residents will produce a sample proportion between 0.361 and 0.579.

• We are 95 percent confident that the proportion of all residents in the sample who favor the proposal is between 0.361 and 0.579.

• We are 95 percent confident that the proportion of all residents in the town who favor the proposal is between 0.361 and 0.579.

Tags

CCSS.HSS.IC.B.4

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

Calculate a 99% confidence interval for p.

• (0.652, 0.868)

• (0.691, 0.829)

• (0.678, 0.842(

• (0.685, 0.895)

Tags

CCSS.HSS.IC.B.4

A preliminary study suggests that 87% of people agree on an issue. How large must your sample size be so you could be within ± 3% of p calculate at 90% confidence?

• 7

• 466

• 5

• 338

Tags

CCSS.HSS.IC.B.4

For a sample, the 95% confidence interval is (0.202, 0.482).

What is the margin of error of this sample?

• 0.28

• 0.14

• 0.342

• 0.684

Tags

CCSS.HSS.IC.B.4