Suppose the scores of a certain high school diploma testfollow a normal distribution in the population with a mean of 195and standard deviation of 30.
1. About ______ percent of the students have ascore between 135 and 195.
2. About ______ percent of the students have a score between 225and 255.
3. The middle 95% of the students have a score between________ and ________ .
4. Recently class A just had a Math exam, but class B had aVerbal exam.
- Joe in class A has a math score of 160, and all the mathscores in class A have a mean of 140 and a standard deviation of10.
- Eric in class B has a verbal score of 80, and all the verbalscores in class B have a mean of 50 and a standard deviation of12.
Let’s assume students in classes A and B have very similaracademic background, and both classes are hugh classes with lots ofstudents. Then roughly speaking, relative to their respectiveclassmates, who did better in the recent exam, Joe or Eric?
| (A) Joe’s math score 160 is better |
| (B) Eric’s verbal score 80 is better |
| (C) They are about the same |
| (D) We also need the variance of the two data sets to compareJoe’s and Eric’s scores |
5. A sample consists of 26 scores. What is the degrees offreedom for the sample standard deviation??
