FORMULAS FOR EXAM 1 1) Coefficient of variation (CV): CV=

std.dev 100% mean

min value  max value 2 3) Range= max value min value 2) Mid-range=

4) Minimum usual & maximum usual values Min usual= mean -2* standard deviation Max usual = mean +2* standard deviation 5) Z-score =

datavalue  mean . Then round off z to two decimal places std .dev

6) Class width=

max value  min value . Then round up to a convenient number # ofclasses

7) Location i for kth percentile: i th 

k n 100

8) Estimate standard deviation using range rule of thumb: s 

range 4

9) Find percentile of a given x: Percentile of x = total number less than x  total number in the data set *100 10) Round off rule for the mean, standard deviation and variance: carry one more decimal than it is present in the original data 11) Round off rule for percent: round off to 3 significant digits