2. In an examination, 25 students secured the following marks:

\begin{tabular}{|l|l|l|l|l|l|l|l|l|l|l|l|}
\hline 83 & 28 & 90 & 82 & 35 & 35 & 36 & 40 & 41 & 43 & 44 & 45 \\
\hline 48 & 49 & 52 & 58 & 54 & 56 & 56 & 58 & 61 & 62 & 65 & 64 \\
\hline
\end{tabular}

1. Arrange these data in the form of a frequency distribution using the following classes: [tex]$20-29, 30-39, 40-49, 50-59,$[/tex] and [tex]$60-69$[/tex].
2. Arrange the data with cumulative frequencies.



Answer :

Let's tackle the given problem step by step. We have a set of marks secured by 25 students, and we are asked to arrange this data into a frequency distribution using the class intervals [tex]\(20-29\)[/tex], [tex]\(30-39\)[/tex], [tex]\(40-49\)[/tex], [tex]\(50-59\)[/tex], and [tex]\(60-69\)[/tex]. We also need to provide the cumulative frequencies for each interval.

### Step 1: List of Marks
Here are the marks provided:
[tex]\[ 83, 28, 90, 82, 35, 35, 36, 40, 41, 43, 44, 45, 48, 49, 52, 58, 54, 56, 56, 58, 61, 62, 65, 64 \][/tex]

### Step 2: Defining Class Intervals and Frequency Distribution
The class intervals are:
- [tex]\(20-29\)[/tex]
- [tex]\(30-39\)[/tex]
- [tex]\(40-49\)[/tex]
- [tex]\(50-59\)[/tex]
- [tex]\(60-69\)[/tex]

We will now arrange the marks into these intervals and count the number of marks within each interval (frequency distribution).

### Frequency Distribution:
- [tex]\(20-29\)[/tex]: 1 mark
- Marks: [28]
- [tex]\(30-39\)[/tex]: 3 marks
- Marks: [35, 35, 36]
- [tex]\(40-49\)[/tex]: 7 marks
- Marks: [40, 41, 43, 44, 45, 48, 49]
- [tex]\(50-59\)[/tex]: 6 marks
- Marks: [52, 54, 56, 56, 58, 58]
- [tex]\(60-69\)[/tex]: 4 marks
- Marks: [61, 62, 64, 65]

Summarizing the frequency distribution in a table:
[tex]\[ \begin{tabular}{|c|c|} \hline Class Interval & Frequency \\ \hline 20-29 & 1 \\ \hline 30-39 & 3 \\ \hline 40-49 & 7 \\ \hline 50-59 & 6 \\ \hline 60-69 & 4 \\ \hline \end{tabular} \][/tex]

### Step 3: Calculating Cumulative Frequencies
To find the cumulative frequency for each interval, we add the frequencies of all preceding intervals.

- Cumulative frequency for [tex]\(20-29\)[/tex]: 1 (only the first interval)
- Cumulative frequency for [tex]\(30-39\)[/tex]: [tex]\(1 + 3 = 4\)[/tex]
- Cumulative frequency for [tex]\(40-49\)[/tex]: [tex]\(4 + 7 = 11\)[/tex]
- Cumulative frequency for [tex]\(50-59\)[/tex]: [tex]\(11 + 6 = 17\)[/tex]
- Cumulative frequency for [tex]\(60-69\)[/tex]: [tex]\(17 + 4 = 21\)[/tex]

### Cumulative Frequency Table:
[tex]\[ \begin{tabular}{|c|c|} \hline Class Interval & Cumulative Frequency \\ \hline 20-29 & 1 \\ \hline 30-39 & 4 \\ \hline 40-49 & 11 \\ \hline 50-59 & 17 \\ \hline 60-69 & 21 \\ \hline \end{tabular} \][/tex]

### Final Summary:
In summary, the frequency distribution and cumulative frequency table for the given marks are as follows:

[tex]\[ \begin{tabular}{|c|c|c|} \hline Class Interval & Frequency & Cumulative Frequency \\ \hline 20-29 & 1 & 1 \\ \hline 30-39 & 3 & 4 \\ \hline 40-49 & 7 & 11 \\ \hline 50-59 & 6 & 17 \\ \hline 60-69 & 4 & 21 \\ \hline \end{tabular} \][/tex]

This detailed table provides a clear arrangement of the given marks into class intervals with their corresponding frequencies and cumulative frequencies.