AP Stats

Calculate the confidence interval for the population mean at the given level of confidence:  n = 65, σ = 3.14, x = 19.5, c = 0.80

• (18.5, 20.5)
• (19, 20)
• (19.001, 19.999)
• (18.9, 19.8)

Calculate the confidence interval for the population mean at the given level of confidence:  n = 846, σ = 1.04, x = 7.9, c = 0.90

• (7.8412, 7.9588)
  
• (6.999, 7.859)
• (8.844, 9.544)
• (5.999, 6.859)

If the confidence level is 90%, what is the associated critical z value (Z_a/2)?

• 2.557
• -1.645
• 1.645
  
• -2.557

If a sample of 225 students have a mean test score of 90, what is the point estimate?

• 90.5
• 91
• 90
• 90.1

What is required to create a t-distribution?

• Population mean and sample mean
• Population distribution and sample size
• Z-interval 
• Confidence interval

If 656 randomly selected people spend a mean of $86 per week on lunch. What is the best point estimate for the mean amount of money spent per week on lunch for all 656 people?

• $86
• $67
• $80
• $68

Value of t_0.025 for a t-distribution with 25 degrees of freedom.

• -2.060
  
• 2.060
  
• 1.555
• -1.555

The mean number of cookies in a household per family per week for a random sample of 786 families in the state of New York is 67.9 cookies. What is the best point estimate?

• 68
• 78
• 86
• 87

What is a critical Z-Value?

• The boundaries for the area of c under the middle of the standard normal curve.
  
• Determines the Z-value
• The mean of a t-distribution

How do you find the lower bound margin of error?

• Subtract E from the X value
  
• Use the Z interval
• Subtract the mean from the confidence value
• Add E to the the X value