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Describing probability
The language of chance (impossible, unlikely, even chance, likely, certain) and the probability scale from 0 to 1.
The probability scale
Probabilities can be written as fractions, decimals or percentages: $\tfrac{1}{4} = 0.25 = 25\%$.
Describe each event: (a) rolling a $7$ on a normal die, (b) a coin landing heads, (c) the sun rising tomorrow.
Rolling a $7$ on a six-sided die is:
There is no $7$.
A fair coin lands tails. This is:
$P = \tfrac{1}{2}$.
Which cannot be a probability?
Probabilities are between $0$ and $1$.
A probability of $0.15$ is best described as:
It is less than $0.5$.
Write $25\%$ as a decimal probability.
$25 \div 100$.
A bag has $9$ red and $1$ blue marble. Picking red is:
$P = 0.9$.
What is the probability of a certain event?
Certain means $1$.
Which is most likely?
$0.7$ is the largest.
New numbers every time. Keep going until you get five in a row.