Skill: Write probability as a percent

A probability can be written as a percent from $(0\%)$ to $(100\%)$.

• $(0\%)$ means impossible.
• $(100\%)$ means certain.
• To change a fraction or decimal to a percent, multiply by $(100\%)$.

Example: A bag has $(12)$ marbles. $3$ are red. What is the probability of choosing a red marble, written as a percent?

1. Write the probability as a fraction:

$$\frac{\text{favorable outcomes}}{\text{total outcomes}}=\frac{3}{12}$$

2. Simplify the fraction:

$$\frac{3}{12}=\frac{1}{4}$$

3. Change the fraction to a percent. Since $\frac{1}{4}=0.25$, multiply by $(100\%)$:

$$0.25 \times 100\%=25\%$$

So, the probability of choosing a red marble is $(25\%)$.

The values $\frac{1}{4}$, $(0.25)$, and $(25\%)$ all represent the same probability.