Find the mean first = sum of scores/number of scores
Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.
Standard deviation = square root of variance
Z = (mean1 - mean2)/standard error (SE) of difference between means
SEdiff = √(SEmean1^2 + SEmean2^2)
SEm = SD/√n
If only one SD is provided, you can use just that to determine SEdiff.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to your Z score.
I'll let you do the calculations.
Episodes of dehydration are common at outdoors music festivals. At a particular large annual event, a first
aid team has recorded over the years 85 cases on average per day. In 2018, during a weekend they observe 78, 86,
79, and 81 cases. Assuming the distributions of cases is normal, can you confirm that the number of cases has
significantly dropped in 2018? Assume alpha=0.10
1 answer
2 answers