Question

Which of the following scores has the better relative position ( as measured by the z score) a. A score of 53 on a test for which the sample mean is 50. b. A score of 230 on a test for which the sample mean is 200. c. A score of 480 on a test for which the sample mean is 400. d. Cannot be determined with the information provided.

Answer 1

d. Cannot be determined with the information provided.

Explanation:

Z-score:

In a set with mean
`\mu` and standard deviation
`\sigma`, the z-score of a measure X is given by:

`Z = (X - \mu)/(\sigma)`

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.

Finding the better relative position:

The score with the better relative position is the one with a higher z-score.

To find the z-score, the mean and the standard deviation is needed, and in this question, the standard deviation is not given, and thus, the correct answer is given by option d.