Math Problem Statement

Bir sürekli rastgele değişken X’in olasılık dağılım fonksiyonu 0 < X < 8 için f(x) = 3(8x - x^2)/256 olarak verilmiştir. Kümülatif dağılım fonksiyonunu ve aşağıdaki olasılıkları hesaplayınız: (a) P(X < 2), (b) P(X < 9), (c) P(2 < X < 4), (d) P(X > 6), (e) P(X < x) = 0.95 ise x=?

Solution

To solve this question, let's break down the tasks step-by-step.

1. Identify the Probability Density Function (PDF):

The PDF f(x)=3(8xx2)256f(x) = \frac{3(8x - x^2)}{256} is defined over the interval 0<X<80 < X < 8.

2. Compute the Cumulative Distribution Function (CDF), F(x)F(x):

The CDF, F(x)F(x), is obtained by integrating f(x)f(x) from the lower bound (0) to xx: F(x)=0xf(t)dt=0x3(8tt2)256dtF(x) = \int_0^x f(t) \, dt = \int_0^x \frac{3(8t - t^2)}{256} \, dt This integral will give us F(x)F(x), the cumulative distribution function, which we will use to calculate the probabilities.

3. Calculate the Given Probabilities:

Using the CDF F(x)F(x), we can evaluate each probability:

  • (a) P(X<2)=F(2)P(X < 2) = F(2)
  • (b) P(X<9)P(X < 9) (Note: Since XX is defined only on 0<X<80 < X < 8, P(X<9)=P(X<8)=1P(X < 9) = P(X < 8) = 1)
  • (c) P(2<X<4)=F(4)F(2)P(2 < X < 4) = F(4) - F(2)
  • (d) P(X>6)=1F(6)P(X > 6) = 1 - F(6)

4. Determine xx for P(X<x)=0.95P(X < x) = 0.95:

For part (e), we need to find xx such that F(x)=0.95F(x) = 0.95. This involves solving for xx in the equation: F(x)=0.95F(x) = 0.95

I'll proceed with these calculations to provide the exact values for each part.Here are the calculated probabilities for each part:

  1. (a) P(X<2)=5320.15625P(X < 2) = \frac{5}{32} \approx 0.15625
  2. (b) P(X<9)=1P(X < 9) = 1
  3. (c) P(2<X<4)=11320.34375P(2 < X < 4) = \frac{11}{32} \approx 0.34375
  4. (d) P(X>6)=5320.15625P(X > 6) = \frac{5}{32} \approx 0.15625
  5. (e) P(X<x)=0.95P(X < x) = 0.95 yields x6.92x \approx 6.92 (only the real positive solution is meaningful within the interval)

Would you like further details on any of these calculations?


Here are some related questions for further exploration:

  1. How would the cumulative distribution function change if the interval was 0<X<100 < X < 10 instead of 0<X<80 < X < 8?
  2. What is the significance of the CDF reaching 1 at x=8x = 8?
  3. How do we interpret the result P(X<x)=0.95P(X < x) = 0.95 in terms of a quantile?
  4. Can the probability P(X>6)P(X > 6) be determined directly from properties of the distribution without using the CDF?
  5. What steps would you take to verify that this function f(x)f(x) is indeed a valid PDF over the interval?

Tip: For any continuous distribution, remember that the area under the curve of the PDF over its defined interval should equal 1, a property essential for verifying any probability density function.

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Math Problem Analysis

Mathematical Concepts

Probability
Continuous Distributions
Integration
Cumulative Distribution Function (CDF)

Formulas

Probability Density Function (PDF) f(x) = 3(8x - x^2)/256
Cumulative Distribution Function (CDF) F(x) = ∫ f(t) dt from 0 to x
Probability Calculations using CDF values, such as P(X < a) = F(a) and P(a < X < b) = F(b) - F(a)

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Undergraduate (Statistics/Probability)