Mathematics · Statistics · NCERT Examples
Example 1
A complete, independently verified solution for NCERT Example 1.
Mathematics · Chapter 13 · NCERT Examples
Verified NCERT questions and solutionsSolutions are checked independently and follow the supplied NCERT chapter edition.
NCERT Example
Example 1
The marks obtained by 30 Class X students in a 100-mark Mathematics paper are given below. Find the mean marks.
Marks obtained | Number of students |
|---|---|
10 | 1 |
20 | 1 |
36 | 3 |
40 | 4 |
50 | 3 |
56 | 2 |
60 | 4 |
70 | 4 |
72 | 1 |
80 | 1 |
88 | 2 |
92 | 3 |
95 | 1 |
Solution
Board-exam working:
Multiply every observation by its corresponding frequency.
Marks (xᵢ) | Frequency (fᵢ) | fᵢxᵢ |
|---|---|---|
10 | 1 | 10 |
20 | 1 | 20 |
36 | 3 | 108 |
40 | 4 | 160 |
50 | 3 | 150 |
56 | 2 | 112 |
60 | 4 | 240 |
70 | 4 | 280 |
72 | 1 | 72 |
80 | 1 | 80 |
88 | 2 | 176 |
92 | 3 | 276 |
95 | 1 | 95 |