Chapter 7 Problems

2. The first Statistics exam had a mean of 65 and a standard deviation of 10 points; the second had a mean of 80 and a standard deviation of 5 points. Derrick scored an 80 on both tests. Julie scored a 70 on the first test and a 90 on the second. They both total 160 points on the two exams, but Julie claims that her total is better, explain.

4. After examining a child at his 2- year checkup, the boy's pediatrician said that the z-score for his height is relative to American 2- year old was -1.88.

6. The pediatrician in Exercise 4 explains to the parents the most extreme 5% of cases often request special treatment or attention.

A. Does this child fall into that group?

B. What do you need to assume about the heights of 2-year-olds to find your answer to part a?

8. Some IQ tests are standardized to a Normal model with a mean of 100 and a standard deviation of 16.

A. Draw the model for these IQ scores. Clearly label it, showing what the 68-95-99.7 Rule predicts about the scores.

B. In what interval would you expect the central 95% of IQ scores to be found?

C. About what percent of people should have IQ scores above 116?

D. About what percent of people should have IQ scores between 68 and 84?

E. About what percent of people should have IQ scores above 132?

10. What percent of a standard Normal model is found in each region? Be sure to draw a picture first.

A. Z > -2.05

B. Z < -0.33

C. 1.2 < Z < 1.8

D. l z l < 1.28

12. In a standard Normal model, what value(s) of Z cut(s) off the region described? Remember to draw a picture firstA. The lowest 12% B. The highest 30%C. The highest 7%D. The middle 50%

Can someone please help me with chapter 7 in statistics. I am so lost I don't understand a thing about this chapter?