Ratios aren't particularly hard to deal with but it would help to know exactly what you're trying to do.
For example are you being asked to simplify ratios or to distribute quantities in accordance with certain ratios? Neither is particularly hard but they require the use of different mathematical techniques.
For example:
Q1. Simplify the ratio 120:200, reducing it to its simplest terms.
To simplify the ratio, we just need to look for numbers which will divide into both sides (i.e. 'common factors'). For example, you might quickly spot that both sides of the ratio can be divided by 10, so let's do that:
120:200 = 12:20.
Now we look again to see if there's anything which divides (exactly) into both 12 and 20. 4 does, so let's divide by that:
12:20 = 3:5.
Now we look again to see if we can divide further. We can't, so 120:200, reduced to its simplest form, equals 3:5.
(Simplifying ratios is exactly the same as simplifying fractions. If you can do one, you can do the other).
Now let's try sharing something out, according to a given ratio:
Q2: Fred's will leave his money to be shared in the ratio 2:3 between his two children Mary (M) and Peter (P). i.e.
M:P = 2:3
When he dies, he leaves �40,000. How much does each person get?
The trick here is to look at the total number of shares. Mary must get 2 shares, Peter must get 3 shares, so the money has to be divided into 5 shares. Let's do that:
1 share = �40,000 � 5 = �8,000
Now lets give each person the correct amount.
Mary gets two shares = 2 x �8,000 = �16,000
Fred gets 3 shares = 3 x �8,000 = �24,000
For further help, please give us some idea of exactly what you're trying to do.
Chris
(Forner Maths teacher)