91影视

Accuracy of price scanners at Walmart. Refer to Exercise 6.129 (p. 377) and the study of the accuracy of checkout scanners at Walmart stores in California. Recall that the National Institute for Standards and Technology (NIST) mandates that for every 100 items scanned through the electronic checkout scanner at a retail store, no more than two should have an inaccurate price. A study of random items purchased at California Walmart stores found that 8.3% had the wrong price (Tampa Tribune, Nov. 22, 2005). Assume that the study included 1,000 randomly selected items.

a. Identify the population parameter of interest in the study.

b. Set up H0 and Ha for a test to determine if the true proportion of items scanned at California Walmart stores exceeds the 2% NIST standard.

c. Find the test statistic and rejection region (at $\mathit{a}\mathbf{=}\mathbf{0}\mathbf{.}\mathbf{05}$ ) for the test.

d. Give a practical interpretation of the test.

e. What conditions are required for the inference, part d, to be valid? Are these conditions met?

Step by step solution

01

Given Information

The sample proportion of items purchased at California Walmart stores is 0.083.

The sample size is 100.

02

Concept

The conditions required to use one proportion z-test are:

$np=鈮�andn(1-p)鈮�15$

03

Verifying the condition required

e.

Here,

$$\begin{gathered} np=1000脳0.02 \\ =20 \\ >15 \end{gathered}$$

Also,

$$\begin{gathered} n(1-p)=1000脳0.98 \\ =980 \\ >15 \end{gathered}$$

Since both the values are more than 15, the conditions are satisfied.

Unlock Step-by-Step Solutions & Ace Your Exams!

• Full Textbook Solutions

  Get detailed explanations and key concepts

• Unlimited Al creation

  Al flashcards, explanations, exams and more...

• Ads-free access

  To over 500 millions flashcards

• Money-back guarantee

  We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!