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Statistics of store scanner accuracy and a study on wheelchair users who live at home

3.36 The national institute for standards and technonoly mandates that for every 100 items scanned through the electronic checkout scanner at a retail store, no more that 2 should have an inaccurate price. A recent study of the accuracy of checkout scanners at Walmart stores in California was conducted. Of the 60 Walmart stores investigated, 52 violated the NIST scanner accuracy standard. If one of the 60 Walmart stores is randomly selected, what is the probability that the store does not violate the NIST scanner accuracy standard?

3.44 The American Journal of Public Health reported on a study of elderly wheelchair users who live at home. A sample of 306 wheelchair users, age 65 or older, were surveyed about whether they had an injurious fall during the year and whether their home features any one of five structural modifications: bathroom modifications, widened doorways/hallways, kitchen modification, installed railings, and easy open doors. Their responses are summarized in the accompanying table. Suppose we select at random, one of the 306 surveyed wheelchair users.

Home Features Injurious Falls No Falls Totals
All 5 2 7 9
At least 1 but not all 26 162 188
None 20 89 109
Totals 48 258 109

a. Find the probability that the wheelchair user had an injurious fall
b. Find the probability that the wheelchair user had all five features installed in the home
c. Find the probability that the wheelchair user had no falls and none of the features installed in the home

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Hi there,

Thanks for letting me work on your post. Here is my explanation:

3.36. Since among 60 stores, only 8 does not violate the ...

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The expert examines the statistics of a store scanner accuracy and a study on wheelchair users who live at home.

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