RATIO & PROPORTION, PERCENTAGE & AVERAGES
Ratio & Proportion
A proportion is a name we give to a statement that two ratios are equal. It can be written in two ways:
- two equal fractions,
- using a colon, a:b = c:d
When two ratios are equal, then the cross products of the ratios are equal.
That is, for the proportion, a:b = c:d , a x d = b x c
Percent to fraction: x% = x/100
Percentage formula: Rate/100 = Percentage/base
Rate: The percent.
Base: The amount you are taking the percent of.
Percentage: The answer obtained by multiplying the base by the rate
Let a1,a2,a3,……,an be a set of numbers, average = (a1 + a2 + a3,+……+ an)/n