Question: You pick a card at random.
1
2
3
4
5
6
7
8
What is P(not prime)?
Write your answer as a percentage.
1. **State the problem:** We have 8 cards numbered from $1$ to $8$. We want to find the probability that a randomly picked card is **not prime**.
2. **Identify prime numbers between 1 and 8:** The prime numbers are $2, 3, 5, 7$.
3. **Count prime and not prime cards:**
- Number of prime cards = $4$
- Total cards = $8$
- Number of not prime cards = $8 - 4 = 4$
4. **Formula for probability:**
$$P(\text{not prime}) = \frac{\text{Number of not prime cards}}{\text{Total number of cards}}$$
5. **Calculate probability:**
$$P(\text{not prime}) = \frac{4}{8}$$
6. **Simplify the fraction:**
$$P(\text{not prime}) = \frac{\cancel{4}}{\cancel{8}} = \frac{1}{2}$$
7. **Convert to percentage:**
$$P(\text{not prime}) = \frac{1}{2} \times 100 = 50\%$$
**Final answer:** The probability of picking a card that is not prime is **50%**.