Frequency Distribution with Decimals



Frequency Distribution with Decimals

Here's an example showing how to set up a frequency distribution when the data include decimals:

|19.55 |

|20.75 |

|21.28 |

|22.02 |

|22.51 |

|22.55 |

|23.75 |

|24.03 |

|24.24 |

|25.17 |

|25.19 |

|25.7 |

|25.91 |

|26.13 |

|26.13 |

|26.32 |

|26.33 |

|27.01 |

|27.13 |

|27.55 |

|27.57 |

|27.79 |

|28.17 |

|30.46. |

|30.91 |

These values were each obtained by taking the average of 25 values randomly chosen between 0 and 50 (i.e., 625 random numbers were used).

Divide the range by the number of classes (let's use 5 in this case):

(30.91 – 19.55) / 5 = 2.272

So the class width is 2.28 (round up to the next value, in hundredths).

Here's the frequency distribution. I have also included the class boundaries, needed for the histogram, and the midpoints. The boundaries and midpoints should not be rounded off. These midpoints work out to a value in the hundredths; sometimes you need thousandths.

|Class Limits |Frequency |Class Boundaries |Midpoint |

|19.55–21.82 |3 |19.545–21.825 |20.685 |

|21.83–24.10 |5 |21.825–24.105 |22.965 |

|24.11–26.38 |9 |24.105–26.385 |25.245 |

|26.39–28.66 |6 |26.385–28.665 |27.525 |

|28.67–30.94 |2 |28.665–30.945 |29.805 |

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