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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.

Definitions:

Fort Sumter

A sea fort in Charleston, South Carolina, known for two battles of the American Civil War, the first of which marked the war's beginning.

Civil War Began

Referring to the start of the American Civil War in 1861, a conflict between the Northern states (the Union) and the Southern states (the Confederacy) primarily over the issues of slavery and states' rights.

Confederate Congress

The legislative body of the Confederate States of America, existing during the American Civil War from 1861 to 1865.

Conscription

The mandatory enlistment of individuals into the armed forces, often implemented during wartime or national emergencies.