SOLUTION: Please help me solve this problem: {A company makes energy saver bulbs and it is known that the standard deviation of the lives of these bulbs is 150 hours. A sample of 100 bulbs i

Question 672775: Please help me solve this problem: {A company makes energy saver bulbs and it is known that the standard deviation of the lives of these bulbs is 150 hours. A sample of 100 bulbs is taken and finds that the mean life of these bulbs is 2250 hours. What is the probability that this sample mean is within 25 hours of the mean life of all bulbs produced.}
Answer by radh(108) (Show Source): You can put this solution on YOUR website!
Hey there fellow Stats student,

Here, we're asked to find the z-score. The z-score is the relative standing, or technically, how many standard deviations an observation is above or below the mean.

With only 25 hours, we're within 1 standard deviation of the mean. Meaning the z-score is 1.

The empirical rule states that 68% of [data units] lie within 1 standard deviation of the mean. Therefore, I would guess that the answer is 68%. Read up on the Empirical Rule for more specifics.

Hope this helps!

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