NZ Level 3
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Fractions of Quantities (simple non-unit)
Lesson

So far, we've learned that a fraction is part of a whole. In A Part of Something, we learned that the denominator (bottom number) of a fraction tells us how many parts an amount is divided into. For example, $\frac{1}{2}$12 means the amount is divided into $2$2 equal groups, $\frac{1}{4}$14 means the amount is divided into $4$4 equal groups and so on.

For example, if I wanted to find $\frac{1}{5}$15 of $20$20, I could say $20\div5=4$20÷​5=4. This means $\frac{1}{5}\times20=4$15×20=4.

But what if I need to know what more than one part is worth? Let's start by watching a video.

 

In summary

You can find a fraction of an amount by

  • Dividing the total quantity by the denominator, then multiplying the answer by the numerator, OR
  • Multiplying the total quantity by the numerator, then dividing the answer by the denominator.

 

Worked Examples

Question 1
 

Evaluate $25\times\frac{2}{5}$25×25.

 
Question 2

In a survey, $\frac{2}{11}$211 of people said Saturday was their favourite day. If $66$66 people were surveyed, how many people picked Saturday?

Outcomes

NA3-1

Use a range of additive and simple multiplicative strategies with whole numbers, fractions, decimals, and percentages.

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