Homework Help: statistics

Posted by StudentD on Wednesday, August 15, 2012 at 12:34pm.

In a psychology class of 100 students, test scores are normally distributed with a mean of 80 and a standard deviation of 5. Approximately what percentage of students have scores between 70 and 90?

A. 68%

B. 80%

C. 95%

D. 99%

statistics - PsyDAG, Thursday, August 16, 2012 at 1:56pm
You haven't memorized the proportion within 2 standard deviations from the mean?

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.

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