Pie & bar-percentage charts

Japanese school year: Elementary 5

What you learn

Learn how to read and construct divided bar graphs and pie charts, representing parts of a whole as percentages totaling 100%. These charts are widely used in news reports and market research to visualize proportions. A solid grasp of calculating ratios and percentages beforehand will ensure success.

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Key points

This formula calculates the percentage $p$ (%) of a part relative to the whole. Divide the part amount $a$ by the total amount $A$ and multiply by $100$ .

p = \frac{a}{A} \times 100

This formula calculates the central angle $\theta$ for a sector in a pie chart. Multiply a full rotation of $360^\circ$ by the proportion of the part $a$ to the total $A$ ( $\frac{a}{A}$ ).

\theta = 360^\circ \times \frac{a}{A}

This formula calculates the central angle $\theta$ in a pie chart directly from the percentage $p$ (%). Since $100\%$ equals $360^\circ$ ( $1\%$ equals $3.6^\circ$ ), multiply $p$ by $3.6^\circ$ .

\theta = 3.6^\circ \times p

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Practice 1Coming soon