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Histograms

Tables & graphs

Japanese school year: Elementary 6

What you learn

Learn how to construct histograms by dividing continuous data into intervals and plotting frequencies as bar heights. Histograms are extensively used to evaluate data distribution, skewness, and spread. Reviewing frequency distribution tables and standard bar graphs beforehand will provide a smooth foundation.

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Key points

These are basic terms used to organize data. A "class" is each divided interval, "class width" is the size of that interval, and "frequency" is the number of data values in each class.

This formula finds the midpoint (class value) xx of an interval. Adding both ends aa and bb and dividing by 2 gives a single value representing that class.

x=a+b2x = \frac{a + b}{2}

This formula calculates relative frequency frf_r, which is the proportion of data in a class. It divides the class count ff by the total count NN, and the sum of all classes is 1.

fr=fNf_r = \frac{f}{N}

A histogram is a bar graph used to visualize data distribution. It places intervals (classes) on the horizontal axis and frequencies on the vertical axis; taller bars indicate higher data concentration.

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