Confidence Intervals of Proportions

You have no preliminary study to work from. How large must your sample size be so you could be within ± 3% of p at 90% confidence?

• 748

• 1068

• 11

• 1495

Which confidence would result in a wider interval (assuming nothing else changed), 91% or 97%?

• 97%, z* is larger for higher confidence intervals

• 97%, the standard error is larger for higher confidence intervals

• 91%, z* is larger for lower confidence intervals

• 91%, the standard error is smaller for lower confidence intervals

What is the margin of error of this sample?

• 0.28

• 0.14

• 0.342

• 0.684

If 827 represents "no" voters out of 2584, construct a 95% confidence interval for the "no" group.

• [.300,.340]

• [.298,.342]

• [.302,.338]

• [.288,.352]

A random sample of 100 WHS students found that 53 of them were in possession of a pencil. What is the p-hat for this sample?

• 0.53

• 0.5

• 0.47

• 1

The symbol for the sample proportion is __________.

• z*

• p̂

• E

• p

Find the value of z* for a 90% confidence interval.

• -1.96

• 1.645

• 1.440

• -1.598

Find a 95% confidence interval if the proportion of green M&Ms in a bag is 23% and the margin of error is 7%.

• (0.16, 0.30)

• (0.23,0.07)

• (0.17,0.29)

• (0.18, 0.24)

An exit poll for a politician running for mayor found that 305 out of 530 voters sampled would vote for this person, with a margin of error or 4.3%. Find the 95% confidence interval for this candidate.

• (0.5334, 0.6176)

• (0.5755, 6185)

• (0.5325, 0.5755)

• (0.907, 0.993)

What is the point estimate if a 95% confidence interval of the proportion of people who sleep less than 6 hours a night is (0.22, 0.38)

• 0.30

• 0.60

• 0.16

• 0.08