13.1 Standard Deviation and Confidence Interval

Find the 95% confidence interval if the mean is 10 and the margin of error is  $\pm2$  .

•  $2\pm10$  

•  $95\pm2$  

•  $10\pm95$  

•  $10\pm2$  

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CCSS.HSS.IC.B.4

Find the margin of error if confidence interval is 95%, standard deviation is 56, and sample size is 27.

• 21.123

• 20.345

• 2.056

• 25

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CCSS.HSS.IC.B.4

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.

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CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

Previous studies show that the standard deviation for work time is 3 hours, and a survey of 40 students has a mean of 9.8 work hours per week.

The 95% confidence interval is…

• (8.84, 10.76)

• (8.87, 10.73)

• (9.02, 10.58)

• (9.00, 10.60)

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CCSS.HSS.IC.B.4

A sample of 40 people owned an average of 1.35 apple products. It is known from a previous study that the population standard deviation of apple product ownership is 0.63 products. Construct a 95% confidence interval.

• (1.11, 1.58)
• (1.15, 1.55)
• (1.19, 1.51)
• (1.09, 1.61)

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CCSS.HSS.ID.A.4

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

What shape is a normal distribution curve?

• Half curve
• Round curve
• Bell curve
• Square curve

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CCSS.HSS.ID.A.2

CCSS.HSS.ID.A.3

According to the empirical rule, what percentage of data falls within 1 standard deviation? 

• 25%
• 68%
• 95%
• 99.7%

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CCSS.HSS.ID.A.4

According to the empirical rule, how much of the data falls within 3 standard deviations? 

• 25%
• 68%
• 95%
• 99.7%

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CCSS.HSS.ID.A.4

Between what two standard deviations of a normal distribution contain 68% of the data?

• one below and one above
• two below and two above
• two below and zero
• zero and two above

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CCSS.HSS.ID.A.4

The mean GPA of students in a course at UCDavis is 3.2 with a standard deviation of 0.3. What percent of students in the course have a GPA between  2.9 and 3.8? 

• 81.5%
• 47.5%
• 68%
• 95%

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CCSS.HSS.ID.A.4