Posted by **luke** on Thursday, April 25, 2013 at 3:28pm.

All deal with a random variable X that follows a normal probability distribution with mean equal to 37 and a standard deviation of 5.

Compute P(X < 39)

Compute P(X < 29 or X > 41)

Compute P(X > 30)

Find the 42nd percentile for this distribution.

- statistics -
**PsyDAG**, Friday, April 26, 2013 at 2:51pm
Z = (score-mean)/SD

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

*Either-or* probabilities are found by adding the individual probabilities.

For last Q, Start with table (.42) and insert Z score into above equation.

- statistics -
**luke**, Friday, April 26, 2013 at 9:30pm
PsyDAG, right on thanks

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