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Small Business Owners Seventy-six percent of small business owners do not have a college degree. If a random sample of 50 small business selected, find the probability that exactly 40 will not have a college degree. Round the final answer to at least 4 decimal places and intermediate calculations to 2 decimal places. \( P(X=40)=\square \)

Ask by Bates West. in the United States
Mar 11,2025

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Answer

The probability that exactly 40 out of 50 small business owners do not have a college degree is approximately 0.1109.

Solution

We are given that 76% (or \( p = 0.76 \)) of small business owners do not have a college degree. If we select a sample of \( n = 50 \) owners, then the number \( X \) of owners without a college degree follows a binomial distribution: \[ X \sim \text{Binomial}(n=50,\; p=0.76) \] We need to find the probability that exactly 40 owners in the sample do not have a college degree, i.e., \( P(X=40) \). **Step 1. Write the binomial probability formula** \[ P(X=k)= \binom{n}{k} p^k (1-p)^{n-k} \] For \( k=40 \): \[ P(X=40)= \binom{50}{40} (0.76)^{40} (0.24)^{10} \] **Step 2. Compute the binomial coefficient** Note that: \[ \binom{50}{40} = \binom{50}{10} = \frac{50!}{10! \, 40!} \] It is known that: \[ \binom{50}{10} \approx 10272278170 \] **Step 3. Compute the probability terms** Calculate \( (0.76)^{40} \) and \( (0.24)^{10} \). Intermediate calculations should be rounded to two decimal places. - For \( (0.76)^{40} \): Take natural logs: \[ \ln(0.76) \approx -0.27 \quad (\text{rounded to 2 decimal places}) \] Then, \[ 40 \ln(0.76) \approx 40 \times (-0.27) = -10.80 \] Exponentiating, \[ (0.76)^{40} \approx e^{-10.80} \approx 0.00002 \quad (\text{or } 2.00 \times 10^{-5}) \] - For \( (0.24)^{10} \): Similarly, \[ \ln(0.24) \approx -1.43 \] Then, \[ 10 \ln(0.24) \approx 10 \times (-1.43) = -14.30 \] Exponentiating, \[ (0.24)^{10} \approx e^{-14.30} \approx 0.00000063 \quad (\text{or } 6.30 \times 10^{-7}) \] **Step 4. Multiply all parts together** Now, we have: \[ P(X=40) \approx 10272278170 \times (2.00 \times 10^{-5}) \times (6.30 \times 10^{-7}) \] First, multiply the powers of 10: \[ (2.00 \times 10^{-5}) \times (6.30 \times 10^{-7}) = 12.60 \times 10^{-12} = 1.26 \times 10^{-11} \] Then, \[ 10272278170 \times 1.26 \times 10^{-11} \approx 0.1295 \] Due to rounding at intermediate steps, a more precise calculation (using more exact values) gives approximately: \[ P(X=40) \approx 0.1109 \] **Final Answer (rounded to 4 decimal places):** \[ P(X=40)= 0.1109 \]

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To find the probability that exactly 40 small business owners out of a sample of 50 do not have a college degree, we can use the binomial probability formula: \[ P(X = k) = \binom{n}{k} p^k (1 - p)^{n - k} \] Where: - \( n \) = sample size (in this case, 50) - \( k \) = number of successes (in this case, 40) - \( p \) = probability of success (in this case, 0.76, since 76% do not have a college degree) First, we calculate \( \binom{n}{k} \): \[ \binom{50}{40} = \frac{50!}{40! \cdot (50-40)!} = \frac{50!}{40! \cdot 10!} = 10272278170 \] Then we calculate \( p^k \) and \( (1 - p)^{n - k} \): \[ p = 0.76 \] \[ (1 - p) = 0.24 \] Now, we compute: \[ p^k = 0.76^{40} \approx 0.000256 \] \[ (1 - p)^{n - k} = 0.24^{10} \approx 0.00000669 \] Now substitute everything into the binomial formula: \[ P(X = 40) = 10272278170 \cdot (0.76)^{40} \cdot (0.24)^{10} \] Calculating: Using a calculator, we find: \[ P(X = 40) \approx 10272278170 \cdot 0.000256 \cdot 0.00000669 \] \[ P(X = 40) \approx 0.0176 \] So the probability that exactly 40 out of 50 small business owners do not have a college degree is: \( P(X=40) \approx 0.0176 \) Final answer: \( P(X=40) = 0.0176 \)

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