# NCERT Class 11-Math՚s: Exemplar Chapter – 15 Statistics Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 2**:

Find the variance and standard deviation for the following data:

**Answer**:

Standard deviation

**Question 3**:

Show that the two formulae for the standard deviation of ungrouped data.

Are equivalent.

**Answer**:

We have

Dividing both sides by n and taking their square root, we get .

**Question 4**:

Calculate variance of the following data:

Class interval | Frequency |

**Answer**:

## Long Answer Type

**Question 5**:

Calculate mean, variation and standard deviation of the following frequency distribution:

Classes | Frequency |

**Answer**:

Let A, the assumed mean, be . Here

Classes | |||||

Variance