A manufacturer knows that their items have a normally distributed lifespan, with a mean of 12.8 years, and standard deviation of 2.4 years. If 22 items are picked at random, 7% of the time their mean life will be less than how many years? Give your answer to one decimal place.
It is given that
Mean=12.8 Years and Standard deviation=2.4 Years
We have to calculate that,7% of the time their mean life will be less than how many years. It means,
It is known that from Z table, the value of Z at 0.07 probability is =-1.476
Thus,7% of the time their mean life will be less than 12.0 years.
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