What does a 2:1 ratio mean?

Question

Ana Robertson · Accepted Answer

A ratio is a comparison between two (or more) different quantities of the same unit.
A ratio does not tell us how many there are altogether, only how their numbers compare.
For example if the numbers of boys and girls at a hockey match are in the ratio 2:1, we know the following information:
- There are more boys than girls.
- There are 2 boys for every girl
- The number of boys is double the number of girls, which is the same as saying there are half as many girls as boys.
- We do not know the total number of people at the match, but we do know that it is a multiple of 3.
-

\frac{2}{3}

of the group are boys and

\frac{1}{3}

are girls.
If we are told that there are 720 people at the match, we will know that there are 480 boys and 240 girls.

\frac{2}{3} \times 720 = 480

boys and

\frac{1}{3} \times 720 = 240

girls.

Joseph Lewis · Accepted Answer

The number is split into two parts such that one is twice as large as the other.
Explanation:
For example, if you split 12 as a 2:1 ratio, you get 8 and 4 (one part twice is large as the other).
In general terms, you can work out the values like this:
Ratio: a:b
Number

= x

= (\frac{x}{a + b}) \cdot a : (\frac{x}{a + b}) \cdot b

What does a 2:1 ratio mean?

Answered question

Answer & Explanation

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