3.8.3: z-Scores

What is the purpose of z-scores?

• to describe the exact location of a score within a distribution

• to find the mean of the distribution

• to describe the shape of the distribution

• to find the standard deviation of the distribution

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

Find the z-score value corresponding if the location is below the mean by 2 standard deviations

• +2.00

• -2.00

• +1.25

• -1.00

A data set has a mean of 290 and a standard deviation of 20. Calculate the z-score for 265.

• $z=250.5$

• $z=1.25$

• $z=-1.02$

• $z=-1.25$

What does it mean to have a z-score of  $z=0$  on a quiz?

• It means you did better than zero people.

• It means you scored the same grade as the average grade.

• It means you earned a zero on the quiz.

• It means the average score was a zero.

What percent of scores are below a z-score of  $z=-1.02$ ?  (Use either the attached image of a z-table or use your own copy of the z-table from your notes)

• 15.87%

• 15.39%

• 9.68%

• 84.61%

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

• .0116

• .0089

• .0068

• .0051