1. The heights of American men aged 18 to 24 are approximately Normally distributed with a mean of 68 inches and a standard deviation of 2.5 inches.About what percentage of the men are shorter than 64 inches tall?

1. 0.0548

2. 0.7257

3. 0.9452

4. 0.75

2. A recent Statistics test had a mean of 67.9 with a standard deviation of 12.8.Whatproportionof the grades are greater than 56?

3. What is the area under the standard normal curve with z greater than 1 orz> 1?

1. 0.1587

2. 0.8413

3. 0.1397

4. 0.5398

4. Hour-long TV shows (on broadcast networks) last an average 43 minutes and have a standard deviation of 1.25 minutes without commercials. What proportion of the shows are between 40 and 44 minutes?

5. Adult IQ scores have a bell-shaped distribution with a mean of 100 and a standard deviation of 15.Find the percentage of adults with scores between 85 and 115.

1. 99.7%

2. 95%

3. 100%

4. 68%

6. A recent Statistics test had a mean of 67.9 with a standard deviation of 12.8.Find thez-scoreassociated with the grade of 56.

7. Stephany took the SAT and got a 585 on the math section.(The mean is 500 and the standard deviation is 100.) Jaquan took the ACT and got a 22(The mean is 17 and the standard deviation is 6). Who did better on their test?Justify your answer using statistics.

8. Z-scores

1. represent the number of standard deviations a score is away from the mean.

2. represent the probability of a given score.

3. All of the above

4. None of the above

5. can only be positive

9. IQ test scores are normally distributed with a mean 100 and a standard deviation of 15.An individual's IQ score is found to be 110.What is thez-score corresponding to this value?

1. -0.67

2. 0.67

3. -1.33

4. 1.33

10. A teacher gives a 20-point quiz to 10 students.The scores are listed below.What is the percentile and interpretation that corresponds to the grade of 10?

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1. 50^thpercentile meaning that the student with 10 got a 50% on the quiz.

1. 30^thpercentile meaning that the student with 10 did better than 30% of the students.

1. 50^thpercentile meaning that the student with 10 did better than 50% of the students.

1. 30^thpercentile meaning that the student with 10 got a 30% on the quiz.

1. 30^thpercentile meaning that the student with 10 did worse than 30% of the students.

11. Which of the following properties is true for all Normal density curves?

I. They are symmetric.

II. The curve reaches its peak at the mean and median.

III. 95% percent of the area under the curve is within two standard deviations of the mean.

1. All three statements are correct.

2. II only

3. I and II only

4. I only

5. I and III only

12. Hour-long TV shows (on broadcast networks) last an average 43 minutes and have a standard deviation of 1.25 minutes without commercials. Approximately what percent of shows are less than 41.5 minutes?

13. A radio station claims that the amount of advertising per hour of broadcast time has an average of 19 minutes and a standard deviation equal to 2.6 minutes.You listen to the radio station for one hour, at a randomly selected time, and carefully observe that the amount of advertising time is equal to 21 minutes.What is the z score and correct interpretation associated with the observed time?

1. z = - 0.77 meaning the time is a little less than one standard deviation above the mean.

2. z = 0.77 meaning the time is a little less than one standard deviation below the mean.

3. z = 0.77 meaning the time is a little less than one standard deviation below the mean.

4. z = - 0.77 meaning the time is a little less than one standard deviation below the mean.

14. Hour-long TV shows (on broadcast networks) last an average 43 minutes and have a standard deviation of 1.25 minutes without commercials. What proportion of shows are more than 44.75 minutes?

15. IQ test scores are normally distributed with a mean 100 and a standard deviation of 15.What is the IQ score that corresponds to az-score of 1.96?

1. 115.6

2. 132.1

3. 129.4

4. 122.4

16. A recent Statistics test had a mean of 67.9 with a standard deviation of 12.8.Find and interpret thez-scoreassociated with the grade of 70.

17. The average IQ of students in a particular calculus class is 110, with a standard deviation of 5.The distribution is roughly bell-shaped.Find the percentage of students with an IQ above 125.

1. 13.5%

2. 2.5%

3. 0.15%

4. 2.35%

18. A placement exam for entrance into a math class yields a mean of 80 and a standard deviation of 10. The distribution of the scores is roughly bell-shaped. Find the percentage of scores that lie between 80 and 100

1. 84%

2. 34%

3. 13.5%

4. 47.5%

19. A recent Statistics test had a mean of 67.9 with a standard deviation of 12.8.Find and interpret thepercentilecorresponds to the grade of 70.

20. What is the area (proportion) under the standard normal curve with z less than 1.25 orz< 1.25?

1. 0.2318

2. 0.1056

3. 0.8944

4. 0.7682