Math Problem Statement

Find the mean (μ) and standard deviation (σ) for the given probability distribution table.

Solution

Let's solve this step by step.


Step 1: Compute xP(x)xP(x) for each value of xx.

xxP(x)P(x)xP(x)xP(x)
00.160×0.16=0.000 \times 0.16 = 0.00
10.201×0.20=0.201 \times 0.20 = 0.20
20.212×0.21=0.422 \times 0.21 = 0.42
30.123×0.12=0.363 \times 0.12 = 0.36
40.314×0.31=1.244 \times 0.31 = 1.24

Step 2: Find the mean μ\mu.

The mean is calculated as: μ=xP(x)\mu = \sum xP(x) Adding up the xP(x)xP(x) values: μ=0.00+0.20+0.42+0.36+1.24=2.22\mu = 0.00 + 0.20 + 0.42 + 0.36 + 1.24 = 2.22

So, the mean μ\mu is: μ=2.22\mu = 2.22


Step 3: Compute the values in the standard deviation table.

The formula for the standard deviation σ\sigma is: σ=(xμ)2P(x)\sigma = \sqrt{\sum (x - \mu)^2 \cdot P(x)} First, we compute each row step by step:

xxxμx - \mu(xμ)2(x - \mu)^2(xμ)2P(x)(x - \mu)^2 \cdot P(x)
002.22=2.220 - 2.22 = -2.22(2.22)2=4.93(-2.22)^2 = 4.934.93×0.16=0.78884.93 \times 0.16 = 0.7888
112.22=1.221 - 2.22 = -1.22(1.22)2=1.49(-1.22)^2 = 1.491.49×0.20=0.29801.49 \times 0.20 = 0.2980
222.22=0.222 - 2.22 = -0.22(0.22)2=0.05(-0.22)^2 = 0.050.05×0.21=0.01050.05 \times 0.21 = 0.0105
332.22=0.783 - 2.22 = 0.78(0.78)2=0.61(0.78)^2 = 0.610.61×0.12=0.07320.61 \times 0.12 = 0.0732
442.22=1.784 - 2.22 = 1.78(1.78)2=3.17(1.78)^2 = 3.173.17×0.31=0.98273.17 \times 0.31 = 0.9827

Step 4: Sum (xμ)2P(x)(x - \mu)^2 \cdot P(x).

Add up all the values in the (xμ)2P(x)(x - \mu)^2 \cdot P(x) column: Sum=0.7888+0.2980+0.0105+0.0732+0.9827=2.152\text{Sum} = 0.7888 + 0.2980 + 0.0105 + 0.0732 + 0.9827 = 2.152


Step 5: Find the standard deviation σ\sigma.

The standard deviation is: σ=Sum\sigma = \sqrt{\text{Sum}} σ=2.1521.467\sigma = \sqrt{2.152} \approx 1.467


Final Answers:

  • Mean μ\mu: 2.22
  • Standard Deviation σ\sigma: 1.467

Let me know if you need clarification or a deeper explanation!


Related Questions:

  1. What is the variance, and how is it related to the standard deviation?
  2. How would you interpret this mean and standard deviation in a real-world context?
  3. What happens to μ\mu and σ\sigma if all probabilities P(x)P(x) are equal?
  4. How do we test if this probability distribution is valid?
  5. What are the key differences between a mean and median in a probability distribution?

Tip:

To confirm your calculations, always ensure that the sum of P(x)P(x) equals 1 for a valid probability distribution!

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Math Problem Analysis

Mathematical Concepts

Probability Distribution
Mean of a Discrete Distribution
Standard Deviation

Formulas

Mean (μ) = Σ[x * P(x)]
Variance (σ^2) = Σ[(x - μ)^2 * P(x)]
Standard Deviation (σ) = √Variance

Theorems

The formulas for mean and standard deviation in probability distributions

Suitable Grade Level

Grades 10-12