Basic Fractions Flashcards

All 8 cards in this deck

What does it mean to simplify a fraction to its lowest terms?

Divide the numerator and denominator by their highest common factor.
e.g. $\frac{12}{18}=\frac{2}{3}$

What is an equivalent fraction?

A fraction with the same value, made by multiplying or dividing the numerator and denominator by the same number.
e.g. $\frac{3}{4}=\frac{15}{20}$

How do you find a fraction of a quantity?
e.g. $\frac{3}{5}$ of $40$

Divide by the denominator, then multiply by the numerator.
$40\div5=8$, $8\times3=24$

In the ratio $a:b$, what fraction of the total is the first part?
e.g. the ratio $2:3$

$\frac{a}{a+b}$
For $2:3$ the first part is $\frac{2}{5}$ of the total.

True or false? In the ratio $1:4$, the first quantity is $\frac{1}{4}$ of the total.

False. There are $1+4=5$ parts, so the first quantity is $\frac{1}{5}$ of the total (and $\frac{1}{4}$ of the second quantity).

How do you decide which is bigger, a fraction of one quantity or a fraction of a different quantity?
e.g. $\frac{1}{2}$ of $30$ or $\frac{1}{3}$ of $60$

Work out each fraction of its own quantity, then compare the two amounts.
$15$ and $20$, so $\frac{1}{3}$ of $60$ is bigger.

True or false? $\frac{1}{4}$ of one quantity is always less than $\frac{1}{3}$ of another quantity.

False. The quantities may be different sizes, so you must work out each amount before comparing.

How do you decide which of two fractions of the same quantity gives the larger amount?

e.g. $\frac{3}{5}$ of £30 or $\frac{2}{3}$ of £30

Compare the fractions using a common denominator; the larger fraction gives the larger amount.

$\frac{9}{15}<\frac{10}{15}$, so $\frac{2}{3}$ of £30 is more.