Chapter 1.3, Problem 91E

(a)

To determine

To make: a boxplot of the given data

Answer to Problem 91E

  

Explanation of Solution

Given:

  

Calculation:

The box plot for data from first period statistics class on the number of text messages and calls they had sent or received in the past 24 hours is below:

  

Now to check for outlier, we will calculate IQR and then we will find out the upper and lower limits:

  $\begin{array}{l}IQR=Q_3-Q_1\\ =43-3\\ =40\\ IQRx1.5=40x1.5\\ =60\\ Q_3+60=43+60\\ =103\\ Q_1-60=3-60\\ =-57\end{array}$

Any value above 103 and below -57 would be an outlier thus in this case 118 is an outlier.

Conclusion:

“Thus, box-plot is made for the given data.”

(b)

To determine

To find: whether the given data supports the statement that number of texts is sent by teens

Answer to Problem 91E

No.

Explanation of Solution

In the data set, 4 of the 25 students have sent at least 58 texts during 24 hours.

The data does not support the findings as majority of teenagers are sending on an average 9 texts per day that makes $9\times 30=270$ text in a month which is much below the findings.