Assuming a population is normally distributed with a mean score of 100 and a standard deviation of 10.
A) What is the probability of selecting an item from the population with a score of more than 110?
B) What proportion of the population is expected to have scores above 100?
C) What is the probability of a score between 95 and 110?
D) What is the probability of a score less than 95?
E) What is the probability of a score less than 90 or more than 115?
2. A firm wants to establish an idea of the useful life of its air freshener. Tests of 100 fresheners revealed a mean useful life of 46 hours with a standard deviation of 5 hours. Develop a 95% and a 90% confidence interval for the mean useful life of all air fresheners.
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