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Posted by on Saturday, March 10, 2012 at 3:21pm.

1. A test has a mean of 50, standard deviation of 10.
A. What scores separate the middle 25% from the rest
b. What proportion would be expected to score between 45 and 55
c. What proportion would be expected to score 68 and above

  • statistics - , Sunday, March 11, 2012 at 12:01pm

    Z = (score-mean)/SD

    Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions and their related Z scores.

    A. Find the Z score with .125 between score and mean. Insert ±Z value in the above equation and solve for the scores.

    B and C. Solve for Z scores and use the table.

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