Let’s say that you work for a news agency, which is conducting an exit poll for the MCD (Municipal Corporation of Delhi) elections. You have been tasked with predicting the winner for **ward 75N** (Ashok Vihar). You ask **100 randomly selected voters** from this ward to name the party they had voted for.

The data thus collected is as given in the following table.

Contesting Party | Number of Voters |

BJP | 5 |

INC | 4 |

From this sample, you have to estimate the percentage of voters that may have voted for BJP.

So, you **define X as the proportion of people that voted for BJP**. Then, the frequency distribution for X would be as follows:

x | Frequency |

1 | 5 |

0 | 4 |

Now, you have to find the mean for X, which is equal to (0 + 0 + 0 + … 42 times) + (1 + 1 + 1 + … 58 times), divided by the total frequency, i.e., 100. So, the **mean**

= 0.58, or **58%.**

Also, you would have to find the standard deviation for this sample of 100 voters. Since the mean is 0.58, the sample’s variance =

= 0.2461. So, the **standard deviation** is equal to its square root, i.e., 0.496, or **49.6%**.