Red Even Probability
1. **Problem statement:** A bag contains 5 red balls numbered 1, 2, 3, 4, 5 and 9 white balls numbered 6, 7, 8, 9, 10, 11, 12, 13, 14. We want to find:
(a) The probability that the ball drawn is red and even-numbered.
(b) The probability that the ball drawn is red or even-numbered.
2. **Formula and rules:**
- Probability of an event $A$ is $\Pr(A) = \frac{\text{number of favorable outcomes}}{\text{total number of outcomes}}$.
- For two events $A$ and $B$:
- $\Pr(A \cap B)$ is the probability both $A$ and $B$ occur.
- $\Pr(A \cup B) = \Pr(A) + \Pr(B) - \Pr(A \cap B)$.
3. **Total number of balls:**
$$5 + 9 = 14$$
4. **(a) Probability red and even-numbered:**
- Red balls: $\{1,2,3,4,5\}$
- Even-numbered red balls: $\{2,4\}$ (2 balls)
- So,
$$\Pr(\text{red and even}) = \frac{2}{14} = \frac{1}{7}$$
5. **(b) Probability red or even-numbered:**
- Red balls: 5 balls
- Even-numbered balls: even numbers from 1 to 14 are $2,4,6,8,10,12,14$ (7 balls)
- Red and even balls (intersection): 2 balls (2 and 4)
- Using the formula:
$$\Pr(\text{red or even}) = \Pr(\text{red}) + \Pr(\text{even}) - \Pr(\text{red and even})$$
$$= \frac{5}{14} + \frac{7}{14} - \frac{2}{14} = \frac{10}{14} = \frac{5}{7}$$
**Final answers:**
- (a) $\Pr(\text{red and even}) = \frac{1}{7}$
- (b) $\Pr(\text{red or even}) = \frac{5}{7}$