1. The problem is to represent the approximation of binomial distributions to normal distributions for probabilities $p=0.5$ and $p=0.05$ with sample sizes $n=3, 25, 50$.
2. The binomial distribution $B(n,p)$ can be approximated by a normal distribution $N(\mu, \sigma)$ where:
$$\mu = np$$
$$\sigma = \sqrt{np(1-p)}$$
This approximation is better for larger $n$ and when $p$ is not too close to 0 or 1.
3. For each $p$ and $n$, calculate:
- Mean: $\mu = np$
- Standard deviation: $\sigma = \sqrt{np(1-p)}$
4. Plot the binomial probability mass function (pmf) and overlay the normal probability density function (pdf) with continuity correction by shifting $x$ by 0.5.
5. Example calculations for $p=0.5$:
- $n=3$: $\mu=1.5$, $\sigma=\sqrt{3\times0.5\times0.5}=0.866$
- $n=25$: $\mu=12.5$, $\sigma=\sqrt{25\times0.5\times0.5}=2.5$
- $n=50$: $\mu=25$, $\sigma=\sqrt{50\times0.5\times0.5}=3.535$
6. Example calculations for $p=0.05$:
- $n=3$: $\mu=0.15$, $\sigma=\sqrt{3\times0.05\times0.95}=0.378$
- $n=25$: $\mu=1.25$, $\sigma=\sqrt{25\times0.05\times0.95}=1.089$
- $n=50$: $\mu=2.5$, $\sigma=\sqrt{50\times0.05\times0.95}=1.54$
7. The plots show that as $n$ increases, the binomial distribution approaches the normal distribution more closely.
Final answer: The normal approximation to the binomial distribution improves with larger $n$ and when $p$ is closer to 0.5, as shown by the calculated means and standard deviations and the graphical overlays.
Binomial Normal Approximation 90D8A0
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