Question:
Julie took five test; her scores are as follows:
IQ 110
SAT Math 605
SAT Verbal 590
math Ach. z = 1.3
Science Ach. PR = 84
They want all the z scores. How do you find the Z score for PR?
The Standard Deviation is 15. Mean 100.
Question:
Julie took five test; her scores are as follows:
IQ 110
SAT Math 605
SAT Verbal 590
math Ach. z = 1.3
Science Ach. PR = 84
They want all the z scores. How do you find the Z score for PR?
The Standard Deviation is 15. Mean 100.
PR is a statistic that presumably follows a normal distribution. You have a value for PR, a mean for PR and a standard deviation for PR. You put those into the formula:
$\displaystyle z = \frac{PR - \bar{PR}}{s.d.} = \frac{84 - 100}{15} = -\frac{16}{15}$.
But for my money, it doesn't make sense to say PR has a mean of 100 ..... I would've thought the mean of a percentile was 50 by definition ......
In which case, $\displaystyle z = \frac{PR - \bar{PR}}{s.d.} = \frac{84 - 50}{15} = \frac{34}{15} = 2.27$, correct to 2 dp.
Maybe someone else will jump in and offer their 2 cents worth ....