Confidence Interval Review

The data set pictured represents the number of text messages sent in a month in a SRS of 32 U.S. teenagers. What is the sample mean? (Round to two decimal places)

(a)  

The same data set as before is pictured and represents the number of text messages sent in a month in a SRS of 32 U.S. teenagers. What is the sample standard deviation? (Round to two decimal places)

(a)  

A company determines that the average cost of lunch at its franchise restaurants is $6.48 with a standard deviation of $1.47. Suppose company executives took a simple random sample of 200 franchise restaurants. According to the Central Limit Theorem, what would be approximate mean cost of lunch in the sampling distribution?

(a)  

A company determines that the average cost of lunch at its franchise restaurants is $6.48 with a standard deviation of $1.47. Suppose company executives took a simple random sample of 200 franchise restaurants. According to the Central Limit Theorem, what would be approximate standard deviation in the sampling distribution? (Round to two decimal places)

(a)  

According to the 2010 US Census, about 82% of Americans live in urban areas. In a simple random sample of 400 Americans, about how many people in the sample would be expected to live in urban areas?

• 3280

• 328

• 112

• 72

According to the 2010 US Census, about 82% of Americans live in urban areas. In a simple random sample of 400 Americans, what would be the approximate standard deviation of the sampling distribution?

• .18

• .85

• .91

• 1.9

What z-score would you use if you were looking to construct a confidence interval with a 90% level of confidence?

(a)  

What z-score would you use if you were looking to construct a confidence interval with a 95% level of confidence?

(a)  

What z-score would you use if you were looking to construct a confidence interval with a 99% level of confidence?

(a)  

When constructing a confidence interval for a population mean, what is the margin of error for a 99% confidence interval, with a sample size of 32 and a standard deviation of 80?

• 27.7

• 34.8

• 36.5

• 38.9