Asked by Bob

Maria and Zoe are taking Biology 105 but are in different classes. Maria's class has an average of 78% with a standard deviation of 5% on the midterm, whereas Zoe's class has an average of 83% with a standard deviation of 12%. Assume that scores in both classes follow a normal distribution.

A. Convert Maria's midterm score of 84 to a standard z score.
which is correct?

a. 0.083
b. 0.5
c. 0.2
d. 1.2
e. 6

B Convert Zoe's midterm score of 89 to a standard z score.

a. 1.2
b. 0.5
c. 6
d. 0.917
e. 2.2

C. Who did better relative to her class?
a. Maria
b. Zoe
c. They performed the same.
d. Neither
e. Cannot determine
Answered by drwls
The z score is the difference from the mean divided by the standard deviation FOR THE PARTICULAR CLASS THE PERSON IS IN. in Maria's case the z score is (84-78)/5 = 1.2. The higher positive z score is better relative to the class.

Now see if you can do the other parts of the question.
Answered by Damon
drwls, now at least three of us have answered this, all with the same answer.
Answered by drwls
Hi Damon. Sorry I missed the other posts. At least I wasn't "odd man out" again with my sloppy math.
Answered by cat dog
A)a
B)b
C) c
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