In a population of normally distributed scores, μ =
240 and σ = 20. Approximately what percentage of random
samples of 100 scores would have means with a value in the range
237 to 243
68
31
77
87
For a population of normally distributed scores, μ =
120 and σ = 10, approximately what would be the 95%
confidence interval of the population mean based upon a random
sample of 16 scores with a mean of 110?
105.24 to 106.2
109.7 to 120.3
144.2 to 159.8
105.1 to 114.9
IQ is known to be normally distributed with a mean of 100 and
standard deviation of 15. If a sample mean of 105 for 25
people is found to be a likely event:
We reject the null hypothesis (H0) and adopt the
alternate hypothesis that the sample came from a population with a
lower mean
We conclude that the finding is statistically
non-significant
We know the probability of obtaining this sample falls outside
the central 95% of scores for the sampling distribution of the
mean
We reject the null hypothesis (H0) and adopt the
alternate hypothesis that the sample came from a population with a
higher mean