Answer:
The z-score for the statistics test grade is of 1.11.
The z-score for the calculus test grade is 7.3.
Due to the higher z-score, the student performed better on the calculus test relative to the other students in each class
Step-by-step explanation:
Z-score:
In a set with mean
and standard deviation
, the z-score of a measure X is given by:
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
In this question:
The grade with the higher z-score is better relative to the other students in each class.
Statistics:
Mean of 79 and standard deviation of 4.5, so ![\mu = 79, \sigma = 4.5](https://tex.z-dn.net/?f=%5Cmu%20%3D%2079%2C%20%5Csigma%20%3D%204.5)
Student got 84, so ![X = 84](https://tex.z-dn.net/?f=X%20%3D%2084)
The z-score is:
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
![Z = \frac{84 - 79}{4.5}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7B84%20-%2079%7D%7B4.5%7D)
![Z = 1.11](https://tex.z-dn.net/?f=Z%20%3D%201.11)
The z-score for the statistics test grade is of 1.11.
Calculus:
Mean of 69, standard deviation of 3.7, so ![\mu = 69, \sigma = 3.7](https://tex.z-dn.net/?f=%5Cmu%20%3D%2069%2C%20%5Csigma%20%3D%203.7)
Student got 96, so ![X = 96](https://tex.z-dn.net/?f=X%20%3D%2096)
The z-score is:
![Z = \frac{X - \mu}{\sigma}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Csigma%7D)
![Z = \frac{96 - 69}{3.7}](https://tex.z-dn.net/?f=Z%20%3D%20%5Cfrac%7B96%20-%2069%7D%7B3.7%7D)
![Z = 7.3](https://tex.z-dn.net/?f=Z%20%3D%207.3)
The z-score for the calculus test grade is 7.3.
On which test did the student perform better relative to the other students in each class?
Due to the higher z-score, the student performed better on the calculus test relative to the other students in each class