Homework Help: statistics

Posted by Pat on Saturday, January 28, 2012 at 3:11pm.

Suppose that the mean score of an exam was 77 when taken 30 students took it on time with a standard deviation of 2. A makeup of the same exam is given to 6 students. The retakes averaged a score of 83 with a standard deviation of 2.9. What is the average of the test scores?

statistics - PsyDAG, Sunday, January 29, 2012 at 11:33am
Mean = Σx/n

Σx = n * mean1 = 30 * 77 = 2310

Σx = n * mean2 = 6 * 83 = 498

total mean = (2310+498)/(30+6) = ?

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