Math Problem Statement

Given: X ~ U[30, 180]. What is the probability that a random value of X will be between 70 and 130?

Solution

The problem gives a uniformly distributed random variable XX, denoted as:

XU[30,180]X \sim U[30, 180]

This indicates that XX is uniformly distributed between 30 and 180. We are asked to find the probability that a random value of XX lies between 70 and 130.

Step-by-step Solution:

  1. Uniform Distribution Formula: The probability density function (PDF) of a uniform distribution on the interval [a,b][a, b] is given by:

    f(x)=1bafor axbf(x) = \frac{1}{b - a} \quad \text{for } a \leq x \leq b

    In this case, a=30a = 30 and b=180b = 180. So the PDF is:

    f(x)=118030=1150f(x) = \frac{1}{180 - 30} = \frac{1}{150}

  2. Probability Calculation: The probability that XX lies between 70 and 130 is the ratio of the length of the interval [70,130][70, 130] to the length of the entire interval [30,180][30, 180]:

    P(70X130)=1307018030=60150=0.4P(70 \leq X \leq 130) = \frac{130 - 70}{180 - 30} = \frac{60}{150} = 0.4

Thus, the probability that a random value of XX is between 70 and 130 is 0.4 or 40%.


Would you like more details on the steps involved? Here are 5 related questions to deepen your understanding:

  1. How is the probability density function (PDF) for a uniform distribution derived?
  2. What is the difference between a uniform distribution and other probability distributions like normal or exponential?
  3. How do you calculate the mean and variance of a uniform distribution?
  4. Can the uniform distribution be used to model real-world scenarios, and if so, what examples fit this distribution?
  5. What is the probability of XX lying between other intervals, such as 50 and 120?

Tip: In uniform distributions, probabilities over intervals can be quickly calculated by comparing the length of the desired interval to the total length of the distribution's range.

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Math Problem Analysis

Mathematical Concepts

Probability
Uniform Distribution

Formulas

P(X) = (desired interval length) / (total interval length)
PDF of uniform distribution: f(x) = 1 / (b - a)

Theorems

Uniform Distribution Theorem

Suitable Grade Level

Grades 10-12