Find k such that the function is a probability density function over the given interval. Then write the probability density function. f(x)=kx, 1≤x≤8 What is the value of k? k=1 (Simplify your answer.) What is the probability density function? f(x) = 0

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### Probability Density Function Problem

#### Problem Statement:
Find \( k \) such that the function is a probability density function over the given interval. Then write the probability density function.

\[ f(x) = kx, \quad 1 \leq x \leq 8 \]

---

**What is the value of \( k \)?**

\[ k = \boxed{1} \] (Simplify your answer.)

**What is the probability density function?**

\[ f(x) = \boxed{} \]

---

**Explanation:**

To be a probability density function over the interval \([1, 8]\), the function \( f(x) = kx \) must satisfy two conditions:
1. The function must be non-negative over the entire interval.
2. The total area under the function over the interval must equal 1.

Let's find \( k \) by setting up the integral of \( kx \) from 1 to 8 and setting it equal to 1:

\[ \int_{1}^{8} kx \, dx = 1 \]

\[ k \int_{1}^{8} x \, dx = 1 \]

Evaluating the integral:

\[ k \left[ \frac{x^2}{2} \right]_{1}^{8} = 1 \]

\[ k \left( \frac{8^2}{2} - \frac{1^2}{2} \right) = 1 \]

\[ k \left( \frac{64}{2} - \frac{1}{2} \right) = 1 \]

\[ k \left( 32 - 0.5 \right) = 1 \]

\[ k \left( 31.5 \right) = 1 \]

\[ k = \frac{1}{31.5} \]

Therefore, the value of \( k \) simplifies to \( \frac{1}{31.5} \).

The probability density function \( f(x) \) is then:

\[ f(x) = \frac{x}{31.5} \]
Transcribed Image Text:### Probability Density Function Problem #### Problem Statement: Find \( k \) such that the function is a probability density function over the given interval. Then write the probability density function. \[ f(x) = kx, \quad 1 \leq x \leq 8 \] --- **What is the value of \( k \)?** \[ k = \boxed{1} \] (Simplify your answer.) **What is the probability density function?** \[ f(x) = \boxed{} \] --- **Explanation:** To be a probability density function over the interval \([1, 8]\), the function \( f(x) = kx \) must satisfy two conditions: 1. The function must be non-negative over the entire interval. 2. The total area under the function over the interval must equal 1. Let's find \( k \) by setting up the integral of \( kx \) from 1 to 8 and setting it equal to 1: \[ \int_{1}^{8} kx \, dx = 1 \] \[ k \int_{1}^{8} x \, dx = 1 \] Evaluating the integral: \[ k \left[ \frac{x^2}{2} \right]_{1}^{8} = 1 \] \[ k \left( \frac{8^2}{2} - \frac{1^2}{2} \right) = 1 \] \[ k \left( \frac{64}{2} - \frac{1}{2} \right) = 1 \] \[ k \left( 32 - 0.5 \right) = 1 \] \[ k \left( 31.5 \right) = 1 \] \[ k = \frac{1}{31.5} \] Therefore, the value of \( k \) simplifies to \( \frac{1}{31.5} \). The probability density function \( f(x) \) is then: \[ f(x) = \frac{x}{31.5} \]
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