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September 19, 2014

September 19, 2014

Posted by **Jason** on Tuesday, December 5, 2006 at 1:10am.

(a) Whatis the probability that a random chosen individual has a WAIS score of 105 or higher?

(b) What are the mean and standard deviation of the average WAIS score of x for a SRS of 60 people?

(C) What is the Probability that the average WAIS score of an SRS of 60 people is 105 or higher?

Use z-scores and the normal distribution table for these problems.

For example:

a) Use z-score formula: z = (x - mean)/sd

z = (105 - 100)/15 = 0.33

Look at a normal distribution table using z = 0.33 and determine the area under the curve that would represent this z-score and higher (upper tail of the distribution curve). That would then be your probability.

If a sample size is given, that needs to be computed into the formula:

z = (x - mean)/(sd/sqrt of sample size)

Note: sqrt = square root.

I hope this will get you started.

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