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proportion of customers spend at least $100 on non-book item

Customers at the ASU bookstore spend varying amounts of money on "non-book" items. Historical data show that the amount spent per customer is normally distributed with a mean of $85 and a standard deviation of $30.

a. What proportion of customers spend at least $100 on non-book items?
b. If the proportion you found in part (a) above is considered on a "per customer" basis, it would represent the probability that any given customer spends at least $100. Round your estimate to the nearest 5%. If one check-stand at the store checks out 20 customers per hour, what is the probability that 10 or more of those 20 spend at least $100?

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8. Customers at the ASU bookstore spend varying amounts of money on "non-book" items. Historical data show that the amount spent per customer is normally distributed with a mean of $85 and a standard deviation of $30.

a. What proportion of customers spend at least $100 on non-book items?

Solution. Let X be the amount that customers spend on non-book items. We know that X is normally distributed with a mean of $85 and a standard deviation of $30.

Hence,
...

Solution Summary

The solution finds the customers spend at least $100 on non-book items.

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