Normal Distribution and Percentiles

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

Find the Z-score.

Mean = 22

Standard Deviation: 3.1

x = 29

• 2.26

• 16.45

• -2.26

• 1.26

Find the mean.

Z-score = -1.4

Standard Deviation: 7

x = 20

• 29.8

• 10.2

• -21

• 35

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

The 75th percentile is also know as the

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

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

Which of the following is a formula that describes calculating a z-score?

• Z = (score - mean) / stand. devation

• Z = (mean - score) / stand. dev.

• Z = score/stand. dev/ mean

• Z = dragonball

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

Using this data: 70, 96, 74, 87, 89, 82, 80, 90, 81, 91, 95, 68.

find the mean. (Round to the nearest hundredth)

• 83.58

• 84

• 83.08

• 83