Standard Deviation

Question

The distribution of scores on a history test is close to normal. The scores are adjusted so that the mean score is about µ = 75 and the standard deviation is σ = 5. What percent of the scores fall between 65 and 75

Answer 1

75-65 = 10 = 2 standard deviations from the mean (2 x 5 =10)

95% fall within 2 standard deviations from the mean

Half that or 95/2 = 47.5% fall between 65 and 75