Question
upstudy study bank question image url

Government workers: The Bureau of Labor Statistics reported that \( 15 \% \) of U.S. nonfarm workers are government employees. A randorn sample of 35 workers is drawn. Use the excel spreadsheet as needed. Part: \( 0 / 5 \) Part 1 of 5 (a) Is it appropriate to use the normal approximation to find the probability that less than \( 25 \% \) of the individuals in the sample are government employees? If so, find the probability. If not, explain why not. It (Choose one) \( \mathbf{v} \) appropriate to use the normal curve, since \( n p= \) is not is not

Ask by Morrison Bernard. in the United States
Feb 19,2025

Upstudy AI Solution

Tutor-Verified Answer

Answer

It is appropriate to use the normal approximation because both \( np = 5.25 \) and \( n(1 - p) = 29.75 \) are greater than 5. Using the normal approximation with continuity correction, the probability that less than 25% of the sample are government employees is approximately 93.8%.

Solution

We are told that 15% of nonfarm workers are government employees and that we have a random sample of 35 workers. Let X be the number of government employees in the sample. Then X has a binomial distribution with parameters n = 35 and p = 0.15. Step 1. Check if the normal approximation is appropriate. A common rule‐of‐thumb is that the normal approximation can be used if both   np ≥ 5   and  n(1 – p) ≥ 5. Here,   np = 35 × 0.15 = 5.25   and  n(1 – p) = 35 × 0.85 = 29.75. Thus, both conditions are met (with np just above 5), so it is acceptable to use the normal approximation. Step 2. Find the probability that less than 25% of the sample are government employees. “Less than 25%” means that the sample proportion p̂ < 0.25. Since the sample size is 35, this corresponds to   X < 0.25 × 35 = 8.75. Because X can only take integer values, X < 8.75 means X ≤ 8. For the normal approximation, we find the mean and variance of X:   Mean, μ = np = 5.25.   Variance, σ² = np(1 – p) = 35 × 0.15 × 0.85 = 4.4625.   Standard deviation, σ = √4.4625 ≈ 2.114. We apply a continuity correction to approximate P(X ≤ 8). We use 8 + 0.5 = 8.5. Then, the z-score is   z = (8.5 – 5.25) / 2.114 ≈ 3.25 / 2.114 ≈ 1.54. Using the standard normal distribution, we find   P(Z < 1.54) ≈ 0.938. Thus, the probability that less than 25% of the individuals in the sample are government employees is approximately 93.8%. Final Answer: (a) It is appropriate to use the normal approximation (since np = 5.25 and n(1 – p) = 29.75 are both greater than 5). Using the normal approximation with continuity correction, we find P(p̂ < 0.25) ≈ 0.938.

Answered by UpStudy AI and reviewed by a Professional Tutor

error msg
Explain
Simplify this solution

Beyond the Answer

To determine if it's appropriate to use the normal approximation for a binomial distribution in this case, we need to check the conditions for the Central Limit Theorem, specifically if both \(np\) and \(n(1-p)\) are greater than 5. Here, \(n = 35\) and \(p = 0.15\). Calculating: \[ np = 35 \times 0.15 = 5.25 \] \[ n(1-p) = 35 \times (1 - 0.15) = 35 \times 0.85 = 29.75 \] Since both \(np\) and \(n(1-p)\) are greater than 5, it is **appropriate** to use the normal approximation. Now, we need the standard deviation and mean: - Mean \( \mu = np = 5.25 \) - Standard deviation \( \sigma = \sqrt{np(1-p)} = \sqrt{35 \times 0.15 \times 0.85} \approx 2.635 \) To find the probability that less than 25% of the individuals in the sample are government employees: \( 25\% \) of \( 35 \) is \( 8.75 \) workers. Since we can only have whole workers, we look at \( 8 \) workers. Now we'll apply the normal approximation \( X \sim N(5.25, 2.635^2) \): Using the z-score formula: \[ Z = \frac{X - \mu}{\sigma} = \frac{8 - 5.25}{2.635} \approx 1.042 \] Using a z-table or calculator, we find \( P(Z < 1.042) \approx 0.8508 \). Therefore, the probability that less than \( 25\% \) of the sample are government employees is approximately \( 0.8508 \) or \( 85.08\% \).

Related Questions

Latest Statistics Questions

Try Premium now!
Try Premium and ask Thoth AI unlimited math questions now!
Maybe later Go Premium
Study can be a real struggle
Why not UpStudy it?
Select your plan below
Premium

You can enjoy

Start now
  • Step-by-step explanations
  • 24/7 expert live tutors
  • Unlimited number of questions
  • No interruptions
  • Full access to Answer and Solution
  • Full Access to PDF Chat, UpStudy Chat, Browsing Chat
Basic

Totally free but limited

  • Limited Solution
Welcome to UpStudy!
Please sign in to continue the Thoth AI Chat journey
Continue with Email
Or continue with
By clicking “Sign in”, you agree to our Terms of Use & Privacy Policy