91Ó°ÊÓ

A quantitative data set has been grouped by using limit grouping with equal-width classes.

The lower limit of the first class is 3 .

The upper limit of the first class is 8.

The class width is 6 .

(a)

The class mark for the second class is as follows:

The second class's lower limit is

= First-class lower limit + Class width

=3+6

=9

The second class's top limit is

= First-class upper limit + Class width

=8+6

=14

The breadth of the class is 6.

9-14 is the second class interval.

The following formula is used to calculate the class mark:

$$\begin{gathered} Mark=\frac{Lowerlimitofthesecondclass+Upperlimitofthesecondclass}{2} \\ =\frac{9+14}{2} \\ =11.5 \end{gathered}$$

As a result, the second-class class mark is 11.5.

(b)

The third class intervals are shown below.

The third class's bottom limit is

$$\begin{gathered} =Thelowerlimitofthesecondclass+theclasswidth. \\ =9+6 \\ =15 \end{gathered}$$

The third class's top maximum is

$$\begin{gathered} =Thesecond-classupperlimit+Classwidth \\ =14+6 \\ =20 \end{gathered}$$

The breadth of the class is 6.

The third class interval costs between 15 and 20.

(c)

The fourth class intervals are shown below.

The fourth class's lower limit is

$$\begin{gathered} =Lowerlimitofthethirdclass+Classwidth \\ =15+6 \\ =21 \end{gathered}$$

The fourth class's upper limit is

$$\begin{gathered} =thethirdclass\text{'}supperlimit+theclass\text{'}swidth \\ =20+6 \\ =26. \end{gathered}$$

The breadth of the class is six.

21 - 26 is the fourth class interval.

As a result, the observation 23 is included in the fourth class intervals.