Percentiles and z-scores

Adam's Z-score on a test is +2.5.  What does this mean?

• He'd better start studying.
• He did better than EVERYONE.
• He scored 2.5 standard deviations above the average.
• He did terrible.

Tags

CCSS.HSS.ID.A.4

Joanne's Z-score is -1.5.  What does this mean?

• She didn't take the test yet.
• She scored 1.5 standard deviations below the average.
• She did better than most people.
• No clue

If Gonzalo's score is 87, the class average is 82, and the SD is 4, what is Gonzalo's Z-score?

• -1.25
• +1.25
• +1.20
• +1.02

Tags

CCSS.HSS.ID.A.4

Jill's Z-score on the same test was a +3.0.  (average was 82 and SD was 4).  
What was her actual score?

• 85 %
• 79 %
• 94 %
• 40 %

What is the Z-score for Tina if she got a 31 on the ACT, the mean was 23 and the SD was 4?

• +0.2
• +2.0
• -2.0
• -0.2

Tags

CCSS.HSS.ID.A.4

If I tell you that you scored at the 55th percentile on your final exam, you would know:

• I scored better than or equal to 55% of the class.

• I earned a 55% on the exam
• I failed the exam
• 45% of the class scored worse than I did 

Given the data set: 1, 2, 3, 6, 9, 11, 45, 102, calculate the percentile rank for 11.

• 70
• 62.5
• 72.5
• 75

What percentile is 74 in the following group of data (must be in order)?35, 65, 68, 100, 23, 69, 74, 70, 61, 90, 85, 55

• 60th

• 90th

• 75th

• 27th

What is the 50th percentile of the following student heights:  60 in, 75 in, 70 in, 58 in, 62 in

• 58
• 70
• 75
• 62

Tags

CCSS.6.SP.A.2

CCSS.6.SP.B.5

CCSS.6.SP.A.3

Find the Z-score.

Mean = 22

Standard Deviation: 3.1

x = 29

• 2.26

• 16.45

• -2.26

• 1.26

Tags

CCSS.HSS.ID.A.4