Problem 31.4 A continuous random variable has a pdf 1-즉 0
Continuous Probability Distributions
Probability distributions are of two types, which are continuous probability distributions and discrete probability distributions. A continuous probability distribution contains an infinite number of values. For example, if time is infinite: you could count from 0 to a trillion seconds, billion seconds, so on indefinitely. A discrete probability distribution consists of only a countable set of possible values.
Normal Distribution
Suppose we had to design a bathroom weighing scale, how would we decide what should be the range of the weighing machine? Would we take the highest recorded human weight in history and use that as the upper limit for our weighing scale? This may not be a great idea as the sensitivity of the scale would get reduced if the range is too large. At the same time, if we keep the upper limit too low, it may not be usable for a large percentage of the population!
![### Problem 31.4
A continuous random variable has a probability density function (pdf) given by:
\[
f(x) =
\begin{cases}
1 - \frac{x}{2} & \text{if } 0 < x < 2 \\
0 & \text{otherwise}
\end{cases}
\]
Find the expected value and the variance.
#### Explanation:
- **Probability Density Function (pdf):**
- For the interval \(0 < x < 2\), the function \(f(x) = 1 - \frac{x}{2}\) defines the likelihood of the random variable taking a value within this range.
- Outside this range, the pdf is zero, indicating that the random variable cannot take values outside of \((0, 2)\).
- **Objective:**
- Calculate the **expected value (mean)** and **variance** of the given probability density function.
To solve, one would typically:
1. **Find the Expected Value (E[X]):**
- Use the integral of \(x \cdot f(x)\) over the interval from 0 to 2.
2. **Find the Variance (\(\text{Var}(X)\)):**
- Use the formula \(\text{Var}(X) = E[X^2] - (E[X])^2\), where \(E[X^2]\) is the integral of \(x^2 \cdot f(x)\) over the same interval.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fd4b99f3a-a047-4b53-97f9-2db84098ecdc%2F234d26c1-5a61-4368-b29a-77b4f8d697bc%2Fycx1gtb_processed.jpeg&w=3840&q=75)
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