Percentages and probability

We close the chapter by observing that the percentages we have handled are the same mathematical object we shall meet when studying probability: a number between $0$ and $1$, read in hundredths.

Observation — Percentages as probability

Percentages are the same mathematical object as probabilities (numbers in $[0,1]$ multiplied by $100$): if an urn contains $30$ red balls out of $200$ in total, the relative frequency is $30/200 = 0{,}15 = 15\%$. When we tackle probability in Year Three, the “proportions” of statistics and the “percentages” of everyday life turn out to be the same tool — so it is worth handling them confidently right from now.

The relative frequency $30/200 = 0{,}15$ is as much a statistical proportion as a percentage ($15\%$) as a probability. Mastering percentages today means already having in hand the basic tool of probability.

Links

Topics: Percentages
Concepts: Relative frequency · Percentage · Probability
Skills: Calculating