The Amount of Time It Takes to Serve Each Customer $3 \times 3.7 = 11.1$

question 208

Multiple Choice

The amount of time it takes to serve each customer in a bank is a random variable with a mean of 3.7 minutes and a standard deviation of 2.1 minutes.When you arrive at the bank there are three customers in front of you.The mean of your wait time is $3 \times 3.7 = 11.1$ minutes.The standard deviation of your wait time is $\sqrt { 2.1 ^ { 2 } + 2.1 ^ { 2 } + 2.1 ^ { 2 } } \approx 3.64$ minutes.What assumptions (if any) underlie the calculation of the mean? of the standard deviation?

• A)Mean: that the time for each customer follows a Normal model Standard deviation: that the times for the three customers are independent of one another and that the time for each customer follows a Normal model
• B)Mean: that the times for the three customers are independent of one another Standard deviation: that the times for the three customers are independent of one another
• C)Mean: no assumptions required Standard deviation: that the times for the three customers are independent of one another
• D)Mean: no assumptions required Standard deviation: no assumptions required
• E)Mean: no assumptions required Standard deviation: that the times for the three customers are independent of one another and that the time for each customer follows a Normal model

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Definitions:

Gambler's Fallacy

The erroneous belief that if something occurs more frequently than normal during a given period, it will happen less frequently in the future, or vice versa.

Legal Standards

Accepted principles that guide behavior and proceedings within legal cases.

Critical Thinking

The process of objectively analyzing and evaluating an issue in order to form a judgment.