Download Estimating ...a Population Mean: Sigma Known

Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
Estimating
...a Population Mean: Sigma Known
Solve the problem.
1) Find the critical value z α/2 that corresponds to a degree of confidence of 98%.
1)
Determine whether the given conditions justify using the margin of error E = z α/2 σ/ n when finding a confidence
interval estimate of the population mean μ.
2)
2) The sample size is n = 5, σ = 12.7, and the original population is normally distributed.
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
Use the confidence level and sample data to find the margin of error E.
3) Replacement times for washing machines: 90% confidence; n = 36, x = 10.0 years,
σ = 2.1 years
3)
Use the confidence level and sample data to find a confidence interval for estimating the population μ.
4) Test scores: n = 71, x = 41.8, σ = 7.2; 98 percent
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
4)
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
Use the margin of error, confidence level, and standard deviation σ to find the minimum sample size required to
estimate an unknown population mean μ.
5)
5) Margin of error: $121, confidence level: 95%, σ = $528
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
Answer Key
Testname: 24_ESTIMATION_MEAN_SIGMA
1)
2)
3)
4)
5)
2.33
Yes
0.6 years
39.8 < μ < 43.8
74
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
Estimating
...a Population Mean: Sigma Not Known
Do one of the following, as appropriate: (a) Find the critical value z α/2, (b) find the critical value tα/2, (c) state that
neither the normal nor the t distribution applies.
1) 98%; n = 7; σ = 27; population appears to be normally distributed.
2) 95%; n = 11; σ is known; population appears to be very skewed.
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
1)
2)
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
Find the margin of error.
_
3) 95% confidence interval; n = 91 ; x = 72, s = 11.4
3)
Use the given degree of confidence and sample data to construct a confidence interval for the population mean μ.
Assume that the population has a normal distribution.
4) n = 10, x = 12.8, s = 4.9, 95 percent
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley
4)
Answer Key
Testname: 25_ESTIMATION_MEAN_SIGMANOT
1) z α/2 = 2.33
2) Neither the normal nor the t distribution applies.
3) 2.37
4) 9.29 < μ < 16.31
Elementary Statistics, by M.F. Triola, 10th Ed., Addison Wesley