Math Problem Statement

x (cash prize, $) P(x)

16,000,000 0.00000000705

200,000 0.00000015

10,000 0.000001829

100 0.000154763

7 0.004724435

4 0.008646243

3 0.01420886

0 0.97226371295 **** If the grand prize is

​16,000,000​,

what is the standard deviation of the cash​ prize?

Solution

To calculate the standard deviation of the cash prize, we follow these steps:

Formula for standard deviation:

σ=i=1nP(xi)(xiμ)2\sigma = \sqrt{\sum_{i=1}^{n} P(x_i) \cdot (x_i - \mu)^2}

Where:

  • xix_i = Cash prize
  • P(xi)P(x_i) = Probability of each cash prize
  • μ\mu = Expected value (mean)

Step 1: Calculate the expected value (μ\mu):

μ=i=1nP(xi)xi\mu = \sum_{i=1}^{n} P(x_i) \cdot x_i

Substitute the given values: μ=(16,000,0000.00000000705)+(200,0000.00000015)+(10,0000.000001829)+(1000.000154763)+(70.004724435)+(40.008646243)+(30.01420886)+(00.97226371295)\mu = (16,000,000 \cdot 0.00000000705) + (200,000 \cdot 0.00000015) + (10,000 \cdot 0.000001829) + (100 \cdot 0.000154763) + (7 \cdot 0.004724435) + (4 \cdot 0.008646243) + (3 \cdot 0.01420886) + (0 \cdot 0.97226371295)

Step 2: Compute the variance (σ2\sigma^2):

σ2=i=1nP(xi)(xiμ)2\sigma^2 = \sum_{i=1}^{n} P(x_i) \cdot (x_i - \mu)^2

Substitute μ\mu into the formula: σ2=i=1nP(xi)(xi22xiμ+μ2)\sigma^2 = \sum_{i=1}^{n} P(x_i) \cdot \big(x_i^2 - 2x_i\mu + \mu^2\big)

Step 3: Take the square root to find σ\sigma:

[ \sigma = \sqrt{\sigma^2} \ as np

Data

data = { "x": [16000000, 200000, 10000, 100, 7, 4, 3, 0], "P(x)": [0.00000000705, 0.00000015, 0.000001829, 0.000154763, 0.004724435, 0.008646243, 0.01420886, 0.97226371295] }

Create a DataFrame

df = pd.DataFrame(data)

Step 1: Calculate the expected value (mean)

df the expected value (mean) df['xP(x)'] = df['x'] * df['P(x)'] mean = df['xP(x)'].sum()

Step 2: Calculate the variance

df['(x - mean)^2'] = (df['x'] - mean) ** 2 df['P(x) * (x - mean)^2'] = df['P(x)'] * df['(x - mean)^2'] variance = df['P(x) * (x - mean)^2'].sum()

Step 3: Standard deviation

std_dev = np.sqrt### Results:

  • Expected Value (Mean), μ\mu: $0.29 (approximately)
  • Variance, σ2\sigma^2: 1,810,984.86
  • Standard Deviation, σ\sigma: $1,345.73

Would you like further clarification or details? Here are some related questions:

  1. What does the standard deviation signify in this context?
  2. How would the expected value change if the probabilities were adjusted?
  3. How is variance different from standard deviation in interpretation?
  4. What would the outcome be if the grand prize was increased?
  5. Can you calculate the coefficient of variation (relative risk) using this data?

Tip: Standard deviation helps measure the spread of prizes around the mean, reflecting how likely

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Math Problem Analysis

Mathematical Concepts

Probability
Expected Value
Variance
Standard Deviation

Formulas

Expected Value (Mean): μ = Σ[P(x) * x]
Variance: σ² = Σ[P(x) * (x - μ)²]
Standard Deviation: σ = √(σ²)

Theorems

Law of Total Probability

Suitable Grade Level

Grades 10-12