Age at onset of dementia was determined for sample of adults between the ages of 60 and 75. For 15 subjects, the results were ΣX = 1008, and Σ(X-M)squared = 140.4. Employ this infor to answer the following:
Determine the mean and SD for this data? Please employ language I can understand for working out this problem, thanks. I have to know how to figure this on my own.