# Answer to Question #3946 in Statistics and Probability for susan

Question #3946

A GE light bulb is supposed to last for 1200 hours. In fact, light bulbs of this type last only 1185 hours with a standard deviation of 70 hours. What is the probability that a sample of 100 light bulbs will have an average life of at least 1200 hours?

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## Comments

Assignment Expert21.03.16, 19:08Z is equal to the standardized variable of the average life. In other words, Z is calculated as follows: the average life minus the sample mean of the average life and the result is finally divided by the standard deviation of the average life.

Ella21.03.16, 17:26How do we find what z is?

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