Confidence Interval Review

A simple random sample of 160 travelers determined that the mean cost of a vacation in North America was $264 per day with a standard deviation of $68. Construct a 95% confidence interval for the mean vacation cost per day for all travelers.

Choose the correct type of confidence interval

• 1-Proportion Z interval

• 1 sample z interval for a mean

• 1 sample t interval for a mean

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

CCSS.HSS.ID.A.4

A simple random sample of 50 driver education students showed the pictured number of hours driven at night prior to obtaining their driver's license. Construct a 90% confidence interval for the true mean number of hours students drive.

Choose the correct type of interval.

• 1-Proportion Z interval

• 1 sample z interval for a mean

• 1 sample t interval for a mean

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

CCSS.HSS.ID.A.4

A simple random sample of 730 registered voters shows that 65% of the registered voters favor raising taxes to pay for state parks. A 98% confidence interval for the true proportion of voters who will vote in favor or raising taxes is to be constructed. Which type of confidence interval should you choose?

• 1-Proportion Z interval

• 1 sample z interval for a mean

• 1 sample t interval for a mean

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

Which is NOT a condition for the interval in the previous question?

• SRS

• Sample size should be greater than or equal to 30, or come from a known normal distribution, or have know outliers or skewness in the data

• The population must be 10x the sample size

• nphat≥10, n(1-phat)≥10

In a simple random sample of 482 lawyers, 136 had tried a case in court. A 80% confidence interval for the true proportion of lawyers who tried a case in court is to be constructed. Which type of confidence interval should you choose?

• 1 sample z interval for a mean

• 1 sample t interval for a mean

• 1-Proportion Z interval

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

Suppose that $51,014 was the mean income for all households in 2012. Does the interval ($52,484, $54,394) provide convincing evidence that the mean household income increased in 2013? 

• Yes

• No

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

CCSS.HSS.ID.A.2

Increasing the sample size __________ the width of the confidence interval.

• increases

• decreases

• does not affect

• there is not enough evidence to determine the answer

Tags

CCSS.HSS.IC.B.4

What can you do to reduce the margin of error? (You may choose more than one)

• increase the confidence level

• decrease the confidence level

• increase sample size

• decrease sample size

Tags

CCSS.HSS.IC.B.4

What is the critical value z* for a 99% confidence interval? 

• -2.58
• 1.96
• -1.64
• 2.58

Tags

CCSS.HSS.ID.A.4

Given the interval (1.2, 1.8), what is the point estimate and the margin of error? 

• 1.5, 0.6
• 1.5, 0.3
• 1.2, 0.3
• 1.2, 0.6

Tags

CCSS.HSS.IC.B.4