__6.4 Frequency Polygons__**1.**A

**frequency polygon**is a line graph that connects the midpoints of

each class interval at the top end of each rectangle in a histogram.

**2.**A frequency polygon can be drawn from a

**(a)**Histogram,

**(b)**Frequency table

**3.**Steps for drawing a frequency polygon:

*Add a class with*

**Step 1:***0*frequency before the first class and add also a

class with

*0*frequency after the last class.*Calculate the midpoints or mark the midpoints of the top sides of*

**Step 2:** the rectangular bars including the midpoints of the two

additional classes.

*Joint all the midpoints with straight lines.*

**Step 3:****Example:**

The following frequency table shows the distance travelled by 38 teenagers by motorcycles in one afternoon.

Journey travelled (km) |
Frequency |

55 – 59 |
4 |

60 – 64 |
4 |

65 – 69 |
7 |

70 – 74 |
8 |

75 – 79 |
9 |

80 – 84 |
6 |

Draw a frequency polygon based on the frequency table.

*Solution:*Journey travelled (km) |
Frequency |
Midpoint |

50 – 54 |
0 |
52 |

55 – 59 |
4 |
57 |

60 – 64 |
4 |
62 |

65 – 69 |
7 |
67 |

70 – 74 |
8 |
72 |

75 – 79 |
9 |
77 |

80 – 84 |
6 |
82 |

85 – 89 |
0 |
87 |