Homework Help: statistics

Posted by tammy on Sunday, April 29, 2012 at 6:19pm.

For a normal distribution with a mean of 140 and a standard deviation of 55 find each value requested.

a. What is the minimum score needed to be in the bottom 10% of the distribution?

b. What scores form the boundaries for the middle 75% of the distribution.

statistics - PsyDAG, Monday, April 30, 2012 at 2:29pm
Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion (.10) related to the Z score. Insert values to find score.

Middle 75% = ą .375 between score and mean. Use the same table.

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