Credit Quiz 12 a

What is the value of σ, the standard deviation of heights?

2.70 inches

Approximately what percentage of the heights are between 61.3 and 64 inches?

34%

The following situation applies to the next four questions: The following Normal curve models the heights of women aged 20 to 29. What is the mean height of these women?

64.0 inches

Approximately what percentage of the heights are less than 66.7 inches?

84%

Ezra's friend, Gwen, takes the math portion of the ACT and scores 27. ACT math scores are Normally distributed with a mean of 20.7 and a standard deviation of 5.0. What is the z-score for Gwen's ACT score?

1.26

The following situation applies to the next four questions: Ezra scores 680 on the mathematics portion of the SAT. The distribution of SAT math scores in recent years has been Normal with a mean of 518 and a standard deviation of 114. What is the z-score for Ezra's SAT math score? 1.93

1.42

Normal curve G has a mean of 50 and a standard deviation of 5. Normal curve H has a mean of 50 and a standard deviation of 10. How do the shapes of these two Normal curves compare if they are drawn using the same scale?

Both are centered at 50, but curve G is taller and skinnier than curve H

Suppose the z-score for Gwen's Math ACT score is 1.2, what is the correct interpretation of this z-score?

Gwen's ACT score is 1.2 standard deviations above the mean

Four of the following statements are correct descriptions of a Normal curve. Which one is NOT a characteristic of a Normal curve?

Its spread increases as its mean increases

Suppose Ezra's z-score is 1.50 and Gwen's z-score is 1.20. If we assume that both assessments measure the same kind of ability, who did better: Ezra or Gwen?

ezra