The Average Lifetime of a Light Bulb Is 3,000 Hours $\bar{x}$

question 127

Essay

The average lifetime of a light bulb is 3,000 hours with a standard deviation of 696 hours.A simple random sample of 36 bulbs is taken.
a.What are the expected value,standard deviation,and shape of the sampling distribution of $\bar{x}$ ?
b.What is the probability that the average life in the sample will be between 2,670.56 and 2,809.76 hours?
c.What is the probability that the average life in the sample will be greater than 3,219.24 hours?
d.What is the probability that the average life in the sample will be less than 3,180.96 hours?

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