Posted by **Ashley** on Monday, November 26, 2012 at 8:46pm.

the average student sends about 200 text messages a day with the standard deviation of 25 texts.(show graph)

a.what is the probability that a student sends more than 250 messsages a day?

b.what is the probability that student sends less than 150 text messages a day?

c.what is the probability that a student sends between 180 and 240?

d.what is the probability that a student ssends exactly 250 text messages a day?

e.find the cutoff number fot the middle 60% of text messages sent per day?

f. find the top 25% of the number of text messages sent per day?

g.find the bottom 10% of text messages sent per day

- statistics -
**PsyDAG**, Tuesday, November 27, 2012 at 2:36am
Z = (score-mean)/SD

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

For e, f, g, find the proportion first and use the Z score in the above equation.

Here is the graph:

http://en.wikipedia.org/wiki/Standard_deviation

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