The grades of a science test are normally distributed. Thanh finds that his grade on the test has a z -score of negative 2 point 5 Which statement must be true?
Answer
A
Thanh’s grade is 2 point 5 points below the mean of the test grades.
B
Thanh’s grade is 2 point 5 points above the mean of the test grades.
C
Thanh’s grade is 2 point 5 standard deviations below the mean of the test grades.
D
Thanh’s grade is 2 point 5 standard deviations above the mean of the test grades.