Question

Using the two-sided OC curves for a single-population t-statistic and the information below, what sample size would be required to detect a true mean interior temperature as high as 22.75 if we wanted the power of the test to be at least 0.9? Use the sample standard deviation s as an estimate for ?.

H₀: ?= 22.50

? = 0.05

s = 0.378

20

40

50

30

Answer 1

Using Minitab ,

stat -> power and sample size -> 1 sample t

Testing mean = null (versus ? null)
Calculating power for mean = null + difference
? = 0.05 Assumed standard deviation = 0.378

            Sample Target
Difference    Size   Power Actual Power
      0.25    27     0.9      0.911040

n = 27

since

D) 30 is correct