Question

The grades of a science test are normally distributed. Thanh finds that his grade on the test has a z-score of –2.5. Which of the following statements must be true?
A. Thanh’s grade is 2.5 standard deviations below the mean of the test grades.

B. Thanh’s grade is 2.5 points below the mean of the test grades.

C. Thanh’s grade is 2.5 standard deviations above the mean of the test grades.

D. Thanh’s grade is 2.5 points above the mean of the test grades.

Answer 1

From all those aforementioned, the true statement is: Thanh’s grade is 2.5 standard deviations below the mean of the test grades. The answer to your question is A. I hope this is the answer that you are looking for and it comes to your help.

Answer 2

The right answer is Thanh's grade is 2.5 standard deviations below the mean of the test grades.

The z scores are standard deviations. If, for example, a tool returns a z score of +2.5, it means that the result is a standard deviation of 2.5.

Very high or very low (negative) z scores associated with very low p values are at the ends of the normal distribution.