The Lifetime of a Certain Type of Automobile Tire (In $\mu = 43$

question 52

Multiple Choice

The lifetime of a certain type of automobile tire (in thousands of miles) is normally distributed with mean $\mu = 43$ and standard deviation $\sigma = 5$ . What proportion of tires have lifetimes between 40 and 50 thousand miles?

• A) 0.6450
• B) 2.0000
• C) 0.3550
• D) 1.1935

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Definitions:

Blind Observations

A research method where the observers are unaware of the participants' conditions or the expected outcome of the experiment to prevent bias.

Random Samples

A subset of individuals chosen from a larger set, where each individual has an equal chance of being selected.

Independent Variables

Factors in an experiment that are intentionally changed to observe their effect on dependent variables.

Placebo

A compound that does not have any healing properties, employed as a standard in evaluating new medications.