Unit rates

Japanese school year: Elementary 5

What you learn

Learn how to compare quantities by standardizing amounts to a single unit, such as population density. This method helps compare crowdedness or efficiency across groups of different sizes. Basic understanding of division and operations with decimal numbers is required beforehand.

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Key points

This formula is used to find the per-unit quantity $u$ , such as an amount per $1\text{ m}^2$ or per item. It is calculated by dividing the total quantity $A$ by the base quantity (like area or item count) $B$ .

u = \frac{A}{B}

This formula is used to calculate the total amount $A$ . Multiply the per-unit amount $u$ by the base quantity $B$ (such as area or count). For example, if there are $3$ plants per $1\text{ m}^2$ across $5\text{ m}^2$ , the total is $3 \times 5 = 15$ plants.

A = u \times B

This formula is used to measure how crowded an area is (population density $D$ ). It divides the total population $P$ by the land area $S$ to find the number of residents per $1\text{ km}^2$ .

D = \frac{P}{S}

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Practice 1Coming soon