It Is Known That 70% of the Customers in a Sporting

question 106

Essay

It is known that 70% of the customers in a sporting goods store purchase a pair of running shoes. A random sample of 25 customers is selected. Assume that customers' purchases are made independently, and let x represent the number of customers who purchase running shoes.
a. What is the probability that exactly 18 customers purchase running shoes?
b. What is the probability that no more than 19 customers purchase running shoes?
c. What is the probability that at least 17 customers purchase running shoes?
d. What is the probability that between 17 and 21 customers, inclusively, purchase running shoes?

---

Definitions:

Financial Accounting Standards Board

An independent, nonprofit organization responsible for establishing accounting and financial reporting standards for companies and non-profit organizations in the United States.

Public Company Accounting Oversight Board

A regulatory body established by Congress to oversee the audits of public companies in order to protect investors and the public interest.

Return on Assets Ratio

An indicator of how profitable a company is relative to its total assets, measuring the efficiency of asset use.

Operating Income

The income produced from the normal operations of a company, subtracting operating expenses from gross profit.