Statistic Quiz

Find the Z-score.

Mean = 22

Standard Deviation: 3.1

x = 29

• 2.26

• 16.45

• -2.26

• 1.26

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

A national achievement test is administered annually to 3rd graders. The test has a mean score of 100 and a standard deviation of 15. If Jane's z-score is 1.20, what was her score on the test?

• 82
• 88
• 100
• 118

The sign of the z-score indicates whether the location is above(positive) or below(negative) the mean.

• True

• False

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

• 55% of the class scored the same or worse than you did

• You earned a 55% on the exam

• You failed the exam

• 45% of the class scored worse than you did

The 75th percentile is also know as the

• median
• third quartile
• 1st quartile`
• interquartile range

What is the percentile rank of 74 in the following group of 15 data values? 35, 65, 68, 100, 23, 69, 74, 70, 61, 90, 85, 55, 30, 65, 80

• 73rd

• 90th

• 75th

• 27th

Joanne's score on a test gives her a Z-score is -1.50. What does this mean?

• Joanne didn't take the test yet.

• Joanne's test score is 1.50 standard deviations below the average test score.

• Joanne did better than 1.50 times her peers.

• Joanne's test score, on average, was 1.5 points lower than the other test scores.

More practice: At a recent invitational, Emmett threw the shotput 43.5 feet with an invite mean of 41 and a SD of 3.

Reese ran the 800 in 2 minutes, 1 second with the mean being 2 minutes 46 seconds and SD of 15 seconds.

What were their Z-scores and who performed better?

• Emmett's Z-score was +0.83, Reese's was -3.00. Emmett did better because his Z-score is higher.

• Emmett's Z-score was +0.83, Reese's was -3.00 but Reese did better because in track, lower times are better to have

• Not enough information