Junk mail Direct mail advertisers send solicitations (a.k.a. junk mail) to thousands of potential customers in the hope that some will buy the companys product. The acceptance rate is usually quite low. Suppose a company wants to test the response to a new flyer, and sends it to 1000 people randomly selected from their mailing list of over 200,000 people. They get orders from 123 of the recipients. a) Create a 90% confidence interval for the percentage of people the company contacts who may buy something. b) Explain what this interval means. c) Explain what 90% confidence means. d) The company must decide whether to now do a mass mailing. The mailing wont be cost-effective unless it produces at least a 5% return. What does your confidence interval suggest? Explain.

1 STAT 145 Introduction to Statistics 1 Chapter 3 Numerically Summarizing Data Terms ormulas 3.1 Measures of Central Tendency Objectives: Understand Mean, Median, and Mode Arithmetic Mean: The sum of ALL values or the number of observations Median: Mid value of the data when it is in ascending order Mode: M ost frequent occurrence in the data set Range: Difference between the largest and smallest data values EX.