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.

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- Jan 27th 2008, 02:40 PMCavalryScoutStatistics Homework Help
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. - Jan 27th 2008, 03:13 PMmr fantastic
- Jan 27th 2008, 03:26 PMCavalryScoutStat help
Can you explain what the symbols stand for?

- Jan 27th 2008, 03:45 PMmr fantastic
- Jan 27th 2008, 03:55 PMCavalryScout
PR is percentile and you need a raw score to use that formula according to this formula sheet. Its so confusing.

- Jan 27th 2008, 04:34 PMmr fantastic
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 ....