Question 18442: Thank you for this great opportunity. My excersice is as follows:
Applications of the Standard Normal Distribution
You are given that a score of 87 on an exam is at 94th percentile and that grades are normally distributed.
a) What z score does this represent? I got .94 = 1.555
b) "This is where i have a problem, Given the formula x = SD*Z + mean," If the mean score on the exam is 82, what is the standard deviation?.
Thank you very much for your help (Due date Saturday November 5th/2005)
Regards
Edwin
Answer by khwang(438)   (Show Source):
You can put this solution on YOUR website! I wonder why you got stuck.
when p = 0.94 . z = 1.555 (correct)
b) "This is where i have a problem, Given the formula x = SD*Z + mean
i.e. (x - mean)/ sd = z (regular form)
Now, x = 87, z = 1.555, mean = 82.
You can get the value of SD with baby algebra.
Kenny
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