Confidence Interval for the Mean (SD unknown) 6.2

A sample of 23 European countries found that the mean life expectancy was 80 years with a standard deviation of 7.3. What is the 95% confidence interval for the mean life expectancy in Europe? 

• 55.349 < μ < 95.873
• 64.983 < μ < 89.368
• 76.843 < μ < 83.157
• 70.384 < μ < 80.563

Tags

CCSS.HSS.IC.B.4

A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year with a standard deviation of 23.8 days.  What is the 90% confidence interval for the average days worked of all payroll departments? 

• 301.0 < μ < 319.6
• 298.0 < μ < 322.6
• 302.4 < μ < 318.2
• 314.1 < μ < 316.8

Tags

CCSS.HSS.IC.B.4

Construct a 95% confidence interval for the population mean, μ.  Assume the population has a normal distribution.  A sample of 20 college students had mean annual earnings of $3120 with a standard deviation of $677.

• ($2657, $2891)
• ($2803, $3437)
• ($1324, $1567)
• ($2135, $2567)

Tags

CCSS.HSS.IC.B.4

Construct a 90% confidence interval for the population mean, μ. Assume the population has a normal distribution. A sample of 15 randomly selected students has a grade point average of 2.86 with a standard deviation of 0.78.

• (2.51, 3.21)
• (2.28, 3.66)
• (2.41, 3.42)
• (2.37, 3.56)

Tags

CCSS.HSS.IC.B.4

Construct a 99% confidence interval for the population mean, μ. Assume the population has a normal distribution. A group of 19 randomly selected students has a mean age of 22.4 years with a standard deviation of 3.8 years.

• (19.9, 24.9)
• (17.2, 23.6)
• (16.3, 26.9)
• (18.7, 24.1)

Tags

CCSS.HSS.IC.B.4