Question

Suppose the purchases at a local convenience store are normally distributed with a mean of $10.50 and a standard deviation of $3.35. If 9 customers are randomly selected, what is the probability that the mean purchase amount for these nine customers is above $11.70? Round your answer to three decimals.

Answer 1

Let Xi denote the random variable representing the purchase amounts (in $) of the 9 customers.

Now we are given that:

Now, the probability that the mean purchase amount for the nine customers is above $11.70 is given by:

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