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December 21, 2014

December 21, 2014

Posted by **pusaran** on Saturday, May 19, 2012 at 1:08am.

(a) the time interval before the PC needs upgrading is more than 2 years and 6 months.

(b) the time interval before the PC need upgrading is between 23 and 27 months.

(c) the mean time interval before the PC needs upgrading is at most 25 months out of 25 PCs chosen at random.

- statistic -
**PsyDAG**, Saturday, May 19, 2012 at 11:44ama & b. Z = (score-mean)/SD

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

c. Since you are dealing with means rather than individual scores, Z = (score-mean)/SEm

SEm = SD/√n

Use the same table.

I'll leave the calculations up to you.

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