The Amount of Time It Takes to Serve Each Customer

question 37

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 × 3.7 = 11.1 minutes.The standard deviation of your wait time is
≈ 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:

Inflation

The rate of increase in the general price index for goods and services, leading to a decrease in how much can be bought.

Purchasing Power

The amount of goods or services one can obtain with a single unit of currency, determining its value.

Deflation

A decrease in the general price level of goods and services, often indicating an reduction in the supply of money or credit.

Nominal Interest Rate

The percentage rate at which interest is charged or paid on a loan or investment, not adjusted for inflation.