**Introduction:**

In statistics, a **histogram** is a graphical representation of tabulated frequencies. A
histogram is the graphical form of a table which describes what number of cases comes into particular categories. The categories are generally specified as nonoverlapping intervals of some
variable. The categories (bars) must be adjacent. The histogram is also one of the fundamental tools of quality control.Let us see solve how to histograms in this article.

Let us see how to solve histograms in this section with several examples.

**Example 1:**

The following data represents the increasing population measured annually (in percentage) by the central government since records began in 2000 up to and including 2000. Draw histogram for the Increasing population in percentage vs year(2000-2010).

Year |
Population in % |

2000 |
12 |

2001 |
9 |

2002 |
15 |

2003 |
17 |

2004 |
10.5 |

2005 |
13 |

2006 |
12 |

2007 |
15 |

2008 |
9 |

2009 |
16 |

2010 |
13 |

**Example 2:**

The following data represents the annual mark of the person (in percentage) by the school. Draw histogram for the mark percentage scored by a particular person for all subject.

Subject |
Mark % |

Tamil 1 |
79 |

Tamil 2 |
82 |

English 1 |
89 |

English 2 |
92 |

Maths |
100 |

Physics |
93 |

Chemistry |
95 |

Biology |
99 |

**Solution:**

** **

** ** These examples clearly tells you about how to solve histograms.

**Steps of construction:**

1. Find class limits and class boundaries

2. Find class frequency and construct grouped frequency table

3. Label horizontal axis using continuous scale

4. Label vertical axis for (relative) frequency

5. Draw bars using class boundaries and (relative) frequency

These are the steps which tells how to solve histograms.

**Problem 1**: create a histogram for this data set.

The following is the concentration of mercury in 30 lake trout caught in a major lake

2.2, 3.4, 3.0, 2.6, 3.8, 1.8, 2.8, 3.2, 3.7, 3.5, 1.4, 2.7, 3.6, 1.9, 2.2, 3.0, 3.3, 2.3, 3.3, 3.6, 1.7, 2.6, 3.5, 3.0, 2.9, 3.4, 3.1, 2.4, 3.4, 3.8.

Use boundaries 0.95-1.45, 1.45-1.95, 1.95-2.45, 2.45-2.95, 2.95-3.45, 3.45-3.95.

This is the practice problem which teach you how to solve histograms.