CI Titan Time Practice

400 randomly selected adults were sampled. 328 of those surveyed said that they like Ice Cream. Find the Margin of Error with 95% confidence for this study.

• 0.074

• 0.192

• 0.037

• 0.368

A survey of 280 homeless persons showed that 63 were veterans.  Construct a 90% confidence interval for the proportion of homeless persons who are veterans.

• (0.161 to .289)
• (0.176 to 0.274)
• (0.184 to 0.266)
• (0.167 to 0.283)

Tags

CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

CCSS.HSS.ID.A.4

In a survey of 2480 golfers, 15% said they were left-handed.  The survey's margin of error was 3%.  Construct a confidence interval for the proportion of left-handed golfers.

• (0.18 to 0.21)
• (0.12 to 0.18)
• (0.12 to 0.15)
• (0.11 to .19)

Tags

CCSS.HSS.IC.B.4

Find the minimum sample size needed to be 4% within the true proportion if you are 95% confident and p-hat = 0.6

• 12
• 6
• 961
• 577

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.A.1

CCSS.HSS.IC.B.4

CCSS.HSS.ID.A.4

A research group wishes to estimate the mean amount of time (in hours) that members of a fitness center spend exercising each week. They want to estimate the mean within a margin of error of 0.5 hours with a 95% level of confidence. Previous data suggests that the standard deviation of the population is 2.2. Which of the following is the smallest sample size they could use?

• 60

• 75

• 90

• 180

Tags

CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

A survey of 800 women shoppers found that 17% of them shop on impulse.  What is the 98% confidence interval for the true proportion of women shoppers who shop on impulse? 

• 0.148 < p < 0.192
• 0.136 < p < 0.204
• 0.144 < p < 0.196
• 0.139 < p < 0.201

Which of the following changes to a study would result in a narrower confidence interval?

• increasing the confidence level, increasing the sample size
• decreasing the confidence level, decreasing the sample size
• increasing the confidence level, decreasing the sample size
• decreasing the confidence level, increasing the sample size.