The quiz grades of a math class are given.
81, 75, 68, 97, 69, 81, 89, 74, 75, 82, 91, 90
the grades are normally distributed with a mean of 81 and a standard deviation of 9.2.
what is the z-score of the lowest grade in the quiz?
round the answer to the nearest hundredth.

Explanation:

The z-score is a measure of how far (how many standard deviations) a value is from the mean of the polulation.

Using the symbols z for the z-score, σ for the standard deviation, μ for the mean, and x for the value under study (the quiz grade), the z-score is calculate using the formula:

In this case:

Thus:

A negative value means that the value (the grade) is less than the mean; thus, the lowest grade in the quiz is 1.30 standard deviations below the mean.

c - they will have the same distribution

step-by-step explanation:

this is the only one that could make sense. : )