In a Recent Investigation, the National Highway Traffic Safety Administration

question 29

Essay

In a recent investigation, the National Highway Traffic Safety Administration (NHTSA) found that the Chevrolet Volt and other electric vehicles do not pose a greater risk of fire than gasoline-powered vehicles (The Boston Globe, January 25, 2012). Specifically, it was determined that "no discernible defect trend exists." Suppose a consumer advocacy group wants to verify some of these claims by constructing a chart. The group expects 2% of electric cars to catch fire each month. For each of the last six months, 500 electric car owners are asked if their cars have caught fire. These sample proportions are obtained:
0.010 0.020 0.015 0.030 0.025 0.015.
A) Assuming that the group expectation is correct, construct the centerline and the upper and lower control limits for the chart.
B) Do the consumer group's findings support those of the NHTSA? Explain the answer.

• A) Assuming that the group expectation is correct, construct the centerline and the upper and lower control limits for the chart.
• B) Do the consumer group's findings support those of the NHTSA? Explain the answer.

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Definitions:

Orthopnea

Difficulty in breathing that is relieved by sitting or standing in an upright position, commonly associated with heart and lung diseases.

Orth/o

A prefix meaning straight, correct, or right, used in medical and technical terms.

Pleurisy

An inflammation of the pleura, the membrane surrounding the lungs, which can cause sharp chest pain with breathing.

Pleurodynia

A condition characterized by a sudden and severe pain in the muscles between the ribs or in the diaphragm, often caused by infections.