Exhibit 6-8 The Life Expectancy of a Particular Brand of Tire Is

question 123

Multiple Choice

Exhibit 6-8
The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles.
-Refer to Exhibit 6-8. What is the probability that a randomly selected tire will have a life of at least 30,000 miles?

• A)0.4772
• B)0.9772
• C)0.0228
• D)0.5000

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Definitions:

Observational Study

A study in which a researcher carefully and systematically observes and records behavior without interfering with the behavior; it may involve either naturalistic or laboratory observation.

Exploratory

Research designed to investigate an area or phenomenon that is not well understood, often used to generate hypotheses for further study.

Experimental

Pertaining to a method of research that tests a hypothesis under controlled conditions.

Double-blind

A study or clinical trial design in which neither the participants nor the experimenters know who is receiving a particular treatment, to prevent bias.