# NCERT Class 11-Math's: Exemplar Chapter –15 Statistics Part 2

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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