Introduction to Ratios Flashcards

All 5 cards in this deck

What does the ratio notation $a : b$ mean?

e.g. red : blue $= 3 : 4$

For every $a$ of the first there are $b$ of the second.

e.g. for every 3 red counters there are 4 blue counters.

In the question "write the ratio of the number of cows to the number of sheep", which number is written first?

The number of cows.

The parts go in the order named in the question.

True or false? The ratio $2 : 3$ means the same as the ratio $3 : 2$.

False.

The order of a ratio matters — $2:3$ and $3:2$ describe different situations.

True or false? If red : blue $= 1 : 4$, then $\frac{1}{4}$ of the counters are red.

False.

There are $1+4=5$ parts altogether, so $\frac{1}{5}$ of the counters are red.

How do you find the fraction of the total that one part of a ratio represents?

e.g. red : blue $= 3 : 4$, what fraction are red?

Write that part over the total number of parts.

$\frac{3}{3+4} = \frac{3}{7}$ are red.