section 2.5

Question 1

normal distribution

Answer 1

when the data is grouped and shown on a histogram, the graph is symmetric and bell shaped

Question 2

standard normal distribution

Answer 2

allows all the different normal variables to be converted into one universal bell shaped distribution

Question 3

z score

Answer 3

is the number of standard deviations that given value is above or below its mean

Question 4

usual values

Answer 4

are z scores from -z to +z . unusual values are z-scores outside this range.