Probability Hits 8E613F
1. **Problem Statement:**
We have three independent events A, B, and C representing hits by three guns with probabilities $P(A)=0.5$, $P(B)=0.6$, and $P(C)=0.8$. We want to find:
i) Probability exactly one gun hits the target.
ii) Probability at least two guns hit the target.
2. **Key Formula and Rules:**
Since A, B, and C are independent, the probability of combined events is the product of their probabilities.
3. **Calculations:**
**i) Exactly one hit:**
This means one event occurs and the other two do not.
$$P(\text{exactly one}) = P(A)P(B^c)P(C^c) + P(A^c)P(B)P(C^c) + P(A^c)P(B^c)P(C)$$
Where $P(A^c) = 1 - P(A)$, etc.
Calculate complements:
$P(A^c) = 1 - 0.5 = 0.5$
$P(B^c) = 1 - 0.6 = 0.4$
$P(C^c) = 1 - 0.8 = 0.2$
Calculate each term:
$P(A)P(B^c)P(C^c) = 0.5 \times 0.4 \times 0.2 = 0.04$
$P(A^c)P(B)P(C^c) = 0.5 \times 0.6 \times 0.2 = 0.06$
$P(A^c)P(B^c)P(C) = 0.5 \times 0.4 \times 0.8 = 0.16$
Sum:
$$0.04 + 0.06 + 0.16 = 0.26$$
**ii) At least two hits:**
This means either exactly two or all three hit.
$$P(\text{at least two}) = P(\text{exactly two}) + P(\text{all three})$$
Calculate exactly two hits:
$$P(\text{exactly two}) = P(A)P(B)P(C^c) + P(A)P(B^c)P(C) + P(A^c)P(B)P(C)$$
Calculate each term:
$P(A)P(B)P(C^c) = 0.5 \times 0.6 \times 0.2 = 0.06$
$P(A)P(B^c)P(C) = 0.5 \times 0.4 \times 0.8 = 0.16$
$P(A^c)P(B)P(C) = 0.5 \times 0.6 \times 0.8 = 0.24$
Sum exactly two:
$$0.06 + 0.16 + 0.24 = 0.46$$
Calculate all three hits:
$$P(A)P(B)P(C) = 0.5 \times 0.6 \times 0.8 = 0.24$$
Sum for at least two:
$$0.46 + 0.24 = 0.7$$
4. **Final Answers:**
- Probability exactly one hits the target: $0.26$
- Probability at least two hit the target: $0.7$