The Solution:
Given:
We are required to answer the following questions:
(a) Determine the total number of observations.
[tex]\begin{gathered} \text{ Total number of observations is the sum of all the frequencies.} \\ \text{ T }=3+1+5+6+1+7=23\text{ observations} \end{gathered}[/tex]
(b) The width of each class.
[tex]\begin{gathered} The\text{ width of each class is the size of each class.} \\ Class\text{ Width}=15-7=24-16=8 \end{gathered}[/tex]
(c) The midpoint of the second class is:
[tex]\begin{gathered} The\text{ midpoint of class }16-24. \\ =\frac{24-16}{2}=\frac{8}{2}=4 \\ \\ So,\text{ }16+4=20 \\ \text{ Thus, the midpoint of the second class is 20.} \end{gathered}[/tex]
(d) The modal class is the class with the highest frequency.
So, the modal class is 52 - 60.
(e) The additional class added is 61 - 68.
The class limit of the additional class is:
[tex]\begin{gathered} 60.5-68.5 \\ the\text{ lower limit is 60.5} \\ the\text{ upper limit is 68.5} \end{gathered}[/tex]