The Number of Phone Calls Arriving at a Switchboard Each

question 55

Multiple Choice

The number of phone calls arriving at a switchboard each hour has been recorded, and the following frequency distribution has been developed.
$$\begin{array} { l c } \text { Class Interval } & \text { Frequency } \\20 \text {-under } 40 & 30 \\40 \text {-under } 60 & 45 \\60 \text {-under } 80 & 80 \\80 \text {-under } 100 & 45\end{array}$$
What is the relative frequency of the second class?

• A)0.455
• B)0.900
• C)0.225
• D)0.750
• E)0.725

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Definitions:

Inspiratory Phase

The period during breathing when air is inhaled into the lungs.

Expiratory Phase

The phase of respiration where air is expelled from the lungs, usually following the inspiratory phase during which air is inhaled.

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