Thread: Statistics 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.

Originally Posted by CavalryScout

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.

, where in this case X = PR = 84.

Can you explain what the symbols stand for?

Originally Posted by CavalryScout

Can you explain what the symbols stand for?

= mean.
= standard deviation.

Maybe you're more comfortable with

PR is percentile and you need a raw score to use that formula according to this formula sheet. Its so confusing.

Originally Posted by CavalryScout

PR is percentile and you need a raw score to use that formula according to this formula sheet. Its so confusing.

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:

.

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, , correct to 2 dp.

Maybe someone else will jump in and offer their 2 cents worth ....