QUIZ 6.1-6.3 CONFIDENCE INTERVALS FOR PROPORTION AND MEAN

In a survey of 250 Internet users, 195 have high-speed Internet access at home.

Find a point estimate for the proportion of all Internet users who have high-speed Internet access at home.

• 1.28

• 0.78

• 195

• 0.22

In a survey of 250 Internet users, 195 have high-speed Internet access at home.

Find a 90% confidence interval for the proportion of all Internet users who have high-speed Internet access at home.

• (0.737, 0.823)

• (0.731, 0.829)

• (0.728, 0.832)

• (1.19, 1.38)

You want to estimate, with 95% confidence, the proportion of households with pets. Your estimate must be accurate within 3% of the population proportion. No preliminary estimate is available. Find the minimum sample size needed

• 1141

• 3267

• 1068

• 1067

In a survey of 1037 adults from the United States age 65 and over, 643 were concerned about getting the flu. (Source: Harvard School for Public Health). Find the minimum sample size needed to estimate the population

proportion at the 99% confidence level in order to ensure that the estimate is accurate within 4% of the population proportion.

• 976

• 977

• 565

• 566

Thirty randomly selected students took the calculus final. If the sample mean was 92 and the standard deviation was 9.4, construct a 99 percent confidence interval for the mean score of all students from which the sample was gathered.

• 89.08 < μ < 94.92

• 87.27 < μ < 96.73

• 87.29 < μ < 96.71

• 87.77 < μ < 96.23

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

CCSS.HSS.ID.A.4

The lifetime of a certain type of batter is known to be normally distributed with a standard deviation of 20 hours. A sample of 50 batteries had a mean lifetime of 120.1 hours. It is desired to construct a 99% confidence interval for the mean lifetime of this type of battery.

What is the Confidence Interval to one decimal place?

• (114.5, 125.6)

• (112.8, 127.4)

• (112.82, 127.38)

• (114.56, 125.64)

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

CCSS.HSS.ID.A.4

A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% confidence interval of the true proportion of cars costing over $700,000?

• 0.001 < p < 0.005
• 0.566 < p < 0.693
• 0.148 < p < 0.252
• 0.023 < p < 0.045

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

CCSS.HSS.ID.A.4

A recent study of 750 Internet users in Europe found that 35% of Internet users were women.  What is the 95% confidence interval of the true proportion of women in Europe who use the Internet? 

• 0.321 < p < 0.379
• 0.316 < p < 0.384
• 0.309 < p < 0.391
• 0.305 < p < 0.395

It was found that in a sample of 90 teenage boys, 70% of them have received speeding tickets.  What is the 90% confidence interval of the true proportion of teenage boys who have received speeding tickets? 

• (0.621, 0.780)
• (0.591, 0.812)
• (0.584, 0.830)
• (0.615, 0.805)

400 randomly selected adults were sampled. The proportion of people who like ice cream was found to be 82%. Find the Margin of Error with 95% confidence for this study. 

• 0.074
• 0.192
• 0.037
• 0.368

Tags

CCSS.HSS.IC.B.4