The Time Between Failures for an Electrical Appliance Is Exponentially

question 1

Multiple Choice

The time between failures for an electrical appliance is exponentially distributed with a mean of 25 months. What is the probability that the next failure will not occur before 30 months have elapsed?

• A) not in excess of .2
• B) in excess of .2 but not in excess of .3
• C) in excess of .3 but not in excess of .4
• D) in excess of .4 but not in excess of .6
• E) in excess of .6

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Definitions:

Independent Variable

In experimental and research settings, the variable that is manipulated to observe its effects on a dependent variable.

Internal Validity

The degree to which a study establishes a trustworthy cause-and-effect relationship between a treatment and an outcome.

Experimental Methods

A research methodology in psychology and other sciences involving the manipulation of variables to determine cause and effect relationships.

Biases

Systematic patterns of deviation from norm or rationality in judgment, whereby inferences about other people and situations may be drawn in an illogical fashion.