In 2011, Brand a MP3 Players Had 45% of the Market

question 88

Essay

In 2011, Brand A MP3 Players had 45% of the market, Brand B had 35%, and Brand C had 20%. This year the makers of brand C launched a heavy advertising campaign. A random sample of electronic stores shows that of 10,000 MP3 Players sold, 4,350 were Brand A, 3,450 were Brand B, and 2,200 were Brand C. Has the market changed? Test at $\alpha$ = 0.01.

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Definitions:

Thoracic Cavity

The chamber of the body of vertebrates that is protected by the thoracic wall and contains the lungs and heart.

Ventral Cavity

A large body cavity that houses many organs, including those in the thoracic and abdominal regions.

Feedback Mechanism

A process in biological and mechanical systems where the system's output is fed back into the system as input, adjusting its performance to meet a desired goal.

Effector

An organ or cell that acts in response to a stimulus, often involved in muscle contraction or gland secretion.