Mat 143 Statistics Empirical Rule and Z Scores

Find the mean.

Z-score = -1.25

Standard Deviation: 4

x = 11

• 16

• 6

• 18

• 21

If heights of 3rd graders follow a normal distribution with a mean of 52 inches and a standard deviation of 2.5 inches, what is the z score of a 3rd grader who is 47 inches tall?

• -5

• -2

• 2

• 5

What is the formula to find the z-score for population?

• z=X-M

• z=σ-M/μ

• ^z/M=μ

• z=X-μ/σ

What is the probability that a score is under (left of) .73?

• .7357

• .7673

• .7389

• .7967

What is the probability that a score is under (left of) 1.73?

• .9484

• .9664

• .9573

• .9582

What is the probability that a score is under (left of) 2.37?

• .9911

• .9913

• .9916

• .9936

What is the probability that a score is under (left of) -.37?

• .6443

• .3974

• .3557

• .3156

What is the probability that a score is above (right of) 2.37?

• .0116

• .0089

• .0068

• .0051

What is the probability that a score is above (right of) -.64?

• .2643

• .7357

• .7389

• .2611

What is the z-score that corresponds to 80.23% of the data to the left?

• .86

• .85

• .83

• .80