The United States Postal Service reports 95 percent of | StudySoup

Textbook Solutions for Basic Statistics for Business and Economics

Chapter 6 Problem 14E

Question

Problem 14E

The United States Postal Service reports 95 percent of first class mail within the same city is delivered within two days of the time of mailing. Six letters are randomly sent to different locations.

a. What is the probability that all six arrive within two days?

b. What is the probability that exactly five arrive within two days?

c. Find the mean number of letters that will arrive within two days.

d. Compute the variance and standard deviation of the number that will arrive within two days.

Solution

Solution

Step 1 of 5

Given that 95% of the first class mail with in the city delivered within 2 days of the mailing

Then

And

Here 6 letters are randomly sent to the different locations

Then

Let X be the no.of letters arrive within 2 days

Here

The pmf of binomial distribution is


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Title Basic Statistics for Business and Economics  7 
Author Douglas Lind; William Marchal; Samuel Wathen
ISBN 9780077384470

The United States Postal Service reports 95 percent of

Chapter 6 textbook questions

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