## Elementary Statistics: A Step-by-Step Approach with Formula Card 9th Edition

Published by McGraw-Hill Education

# Chapter 4 - Probability and Counting Rules - 4-2 The Addition Rules for Probability - Exercises 4-2 - Page 208: 18

#### Answer

a. $0.335$ b. $0.811$ c. $0.598$

#### Work Step by Step

The total is 2784 a. The item went to a home. (add numbers under home 934) P(went to a home)=$934/2784=0.335$ b. The item was an ad, or it went to a business. (all ad 1427, all to business 1850) P(ad)=$1427/2784=0.513$, P(business)=$1850/2784=0.665$ P( ad and to a business)=$1021/2784=0.367$ P( ad or to a business)=$0.513+0.665-0.367=0.811$ c. The item was a first-class letter, or it went to a home. (all letter 1057, all to home 934) P(letter)=$1057/2784=0.380$, P(went to a home)=$934/2784=0.335$ P(letter and went to a home)=$325/2784=0.117$ P(letter or went to a home)=$0.380+0.335-0.117=0.598$

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