assume that the odor threshold for untrained noses is normal with a standard deviation of 7. the odor thresholds for these 10 noses are: 31, 31, 43, 36, 23, 34, 32, 30, 20 and 24. is there evidence that the mean threshold for untrained tasters is greater than 25 micrograms per liter?

Answer 1

Calculate mean.

Z = (score-mean)/SEm = (25-mean)/SEm

SEm = SD/√n

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability
related to the Z score. Would you consider that probability significant?