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Accuracy of price scanners at Wal-Mart. Refer to Exercise
Chapter 7, Problem 122SE(choose chapter or problem)
Accuracy of price scanners at Wal-Mart. Refer to Exercise and the study of the accuracy of checkout scanners at Wal-Mart 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 2 should have an inaccurate price. A study of random items purchased at California Wal-Mart 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 \(H_0\) and \(H_a\) for a test to determine whether the true proportion of items scanned at California Wal-Mart stores exceeds the 2% NIST standard.
c. Find the test statistic and rejection region (at \(\alpha=.05\)) for the test.
d. Give a practical interpretation of the test.
e. What conditions are required for the inference made in part d to be valid? Are these conditions met?
Questions & Answers
QUESTION:
Accuracy of price scanners at Wal-Mart. Refer to Exercise and the study of the accuracy of checkout scanners at Wal-Mart 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 2 should have an inaccurate price. A study of random items purchased at California Wal-Mart 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 \(H_0\) and \(H_a\) for a test to determine whether the true proportion of items scanned at California Wal-Mart stores exceeds the 2% NIST standard.
c. Find the test statistic and rejection region (at \(\alpha=.05\)) for the test.
d. Give a practical interpretation of the test.
e. What conditions are required for the inference made in part d to be valid? Are these conditions met?
ANSWER:Solution
Step 1 of 5
a) We have to identify the population of interest
The population of interest is p= The proportion of items having wrong piece scanned at california Wal Mart stores
Given that 8.3% had a wrong piece
Hence p=0.083