Statistics:
The chapter 'Statistics' typically carrying the weightage of 5-7 marks in the board examination. It covers the concepts like mean, median and mode of grouped data using various methods.
Most possible variation of question types that we can expect in board as per previous year question paper are discussed below.
| Total Marks 5 - 7 | |
| Variation 1 | Variation 2 |
Total Marks \(=6\)
|
Total Marks \(=7\)
|
To prepare well for the board examination, it is necessary to understand the following concepts clearly.
- Mean of grouped data - Mean of grouped data using direct method, assumed mean method and step deviation method and finding missing frequencies.
- Median - Median of grouped data and finding missing frequencies.
- Mode - Mode of grouped data, finding missing frequencies and emprical formula.
| Important Concept(Learning Outcomes) | Expected question type | Concept dealt with |
| Mean of grouped data | Sec C, Sec D | |
| Median of grouped data | Sec B, Sec C, Sec D | |
| Emprical formula | Sec A, Sec B | |
| Mode of grouped data | Sec C, Sec D |
Let us recall the concepts in Statistics:
1. Mean of grouped data:
(i) Direct method \(\bar{x} = \frac{\sum{f_{i}}{x_{i}}}{\sum{f_{i}}}\)
(ii) Assumed mean method \(\bar{x} = a + \frac{\sum{f_{i}}{d_{i}}}{\sum{f_{i}}}\)
(iii) Step deviation method \(\bar{x} = a + \frac{\sum{f_{i}}{u_{i}}}{\sum{f_{i}}} \times h\)
2. Mode of grouped data:
Mode \(= l+(\frac{f_{1}-f_{0}}{2f_{1}-f_{0}-f_{2}}) \times h\)
3. Median of grouped data:
Median \(= l+(\frac{\frac{n}{2}-cf}{f}) \times h\)
4. Empirical relation:
\(3\) Median \(=\) \(2\) Mean \(+\) Mode