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January 27, 2015

January 27, 2015

Posted by **GetYourLeash** on Friday, July 22, 2005 at 1:24am.

You need to change the times to Z-scores — scores given in terms of standard deviations.

Z = (X - µ)/SD, where X is the particular value, µ = the mean and SD is the standard deviation.

Once the Z scores are obtained, look it up in a table in the back of your statistics textbook called something like "areas under the normal distribution." Find the proportions between those Z-scores and the mean for both values and add them together to get the probability that the life of the bulb will be between these two values.

Although I did not solve the problem completely for you, I did tell you the process for reaching a solution. This will mean that you will have to exert a little more effort, time and thinking, but I hope it will help you to learn more.

I hope this helps. Thanks for asking.

huh

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