1. **State the problem:**
Find the probability that a baseball player with a batting average of 0.28 hits exactly 4 times in 12 at-bats.
2. **Formula used:**
This is a binomial probability problem. The formula is:
$$P(X = k) = \binom{n}{k} p^k (1-p)^{n-k}$$
where:
- $n$ is the number of trials (at-bats),
- $k$ is the number of successes (hits),
- $p$ is the probability of success on a single trial,
- $\binom{n}{k}$ is the binomial coefficient.
3. **Calculate the binomial coefficient:**
$$\binom{12}{4} = \frac{12!}{4! (12-4)!} = \frac{12!}{4! 8!}$$
4. **Calculate the probability:**
$$P(X=4) = \binom{12}{4} (0.28)^4 (0.72)^8$$
5. **Intermediate calculation:**
Calculate $\binom{12}{4}$:
$$\binom{12}{4} = \frac{12 \times 11 \times 10 \times 9}{4 \times 3 \times 2 \times 1} = \frac{11880}{24} = 495$$
6. **Substitute values:**
$$P(X=4) = 495 \times (0.28)^4 \times (0.72)^8$$
7. **Calculate powers:**
$$ (0.28)^4 = 0.0061477 \quad \text{(approx)}$$
$$ (0.72)^8 = 0.0587197 \quad \text{(approx)}$$
8. **Multiply all:**
$$P(X=4) = 495 \times 0.0061477 \times 0.0587197 \approx 495 \times 0.0003609 = 0.1786$$
9. **Final answer:**
The probability that the player hits exactly 4 times in 12 at-bats is approximately **0.18**.
---
10. **Next problem:** Explain the "N" in BINS for the same scenario.
11. **Explanation:**
In BINS (Binomial setting), "N" represents the number of trials or attempts.
12. **In this problem:**
The player is at bat 12 times, so $N=12$.
13. **Answer:**
The correct statement is: **He is at bat 12 times**.
Binomial Probability 1Fd283
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.