Final Review IV: Inference

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

The 99% confidence interval for a proportion is (0.54, 0.72). What is p-hat?

• 0.63
• 0.18
• 0.09
• 0.66

The 95% confidence interval of a mean is (0.23, 0.43). What is the margin of error?

• 0.33
• 0.10
• 0.20
• 0.05

Only about 20% of people who try to quit smoking succeed. Sellers of a motivational tape claim that listening to their recorded messages can improve a person's chances of quitting. The results of their hypothesis test are displayed here. Out of the 50 people surveyed, how many were able to quit after using their tape?

• 3
• 20
• 14
• 28

Only about 20% of people who try to quit smoking succeed. Sellers of a motivational tape claim that listening to their recorded messages can improve a person's chances of quitting. The results of their hypothesis test are displayed here. What can we conclude as a result of this study?

• Reject Ho. There IS significant evidence to suggest that people listening to the tapes are more successful at quitting.
  
• Fail to reject Ho. There is not significant evidence to suggest that people listening to the tapes are more successful at quitting.
• Reject Ho. There is not significant evidence to suggest that people listening to the tapes are more successful at quitting.
  
• Accept Ho. There IS significant evidence to suggest that people listening to tapes are more successful at quitting. 

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.

Which of the following is NOT a parameter?

• μ
• σ
• p̂
• p

In a crash test of 15 troopers, collision repair costs are found to have a distribution that is approximately normal, with a mean of $1800 and a standard deviation of $950. Interpret the 99% confidence interval.

• We are 99% confident that the sample mean is between $1070 and $2530.
  
• We are 99% confident that between 1070 and 2530 troopers will be repaired at an average cost of $1800. 
  
• We are 99% confident that the true mean repair cost is between $1070 and $2530.
• There is a 99% chance that the true mean is between $950 and $1800.

Which of the following outcomes of a hypothesis tests would be the weakest evidence against the null. 

• z = 3.5
• p = 0.0001
• p = 0.03
• z = 0

Which is NOT true about inference for means?

• We use a t-distribution to account for greater variability in small samples.
• The standard deviation of a sampling distribution is σ= s/√n
• The Margin of Error can be calculated by z^*(√pq/n).
• The parameter is μ.