Math Problem Statement

The waiting times between a subway departure schedule and the arrival of a passenger are uniformly distributed between 0 and 6 minutes. Find the probability that a randomly selected passenger has a waiting time greater than 2.25 minutes.

Solution

To solve the problem of finding the probability that a randomly selected passenger has a waiting time greater than 2.25 minutes, we need to understand the properties of a uniform distribution.

Given:

  • The waiting times are uniformly distributed between 0 and 6 minutes.

For a uniform distribution U(a,b)U(a, b), the probability density function (PDF) is given by:

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

Here, a=0a = 0 and b=6b = 6. So the PDF is:

f(x)=160=16for0x6f(x) = \frac{1}{6 - 0} = \frac{1}{6} \quad \text{for} \quad 0 \leq x \leq 6

To find the probability that the waiting time XX is greater than 2.25 minutes, we calculate:

P(X>2.25)=1P(X2.25)P(X > 2.25) = 1 - P(X \leq 2.25)

First, we find P(X2.25)P(X \leq 2.25):

P(X2.25)=02.25f(x)dx=02.2516dxP(X \leq 2.25) = \int_{0}^{2.25} f(x) \, dx = \int_{0}^{2.25} \frac{1}{6} \, dx

P(X2.25)=16×2.25=2.256=0.375P(X \leq 2.25) = \frac{1}{6} \times 2.25 = \frac{2.25}{6} = 0.375

Now, we calculate P(X>2.25)P(X > 2.25):

P(X>2.25)=10.375=0.625P(X > 2.25) = 1 - 0.375 = 0.625

Therefore, the probability that a randomly selected passenger has a waiting time greater than 2.25 minutes is 0.625.

Simplified Answer: 0.625 (rounded to three decimal places).

Would you like further details or have any questions?

Here are 5 related questions to expand your understanding:

  1. How do you derive the probability density function for a uniform distribution?
  2. What is the cumulative distribution function (CDF) for a uniform distribution?
  3. How would you calculate the expected value (mean) of a uniformly distributed random variable?
  4. What is the variance of a uniformly distributed random variable between aa and bb?
  5. How would you calculate the probability that the waiting time is less than 4 minutes?

Tip: For any uniform distribution U(a,b)U(a, b), the area under the curve (PDF) always equals 1, representing the total probability.

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Math Problem Analysis

Mathematical Concepts

Probability
Uniform Distribution

Formulas

Probability density function (PDF) for a uniform distribution U(a, b): f(x) = 1 / (b - a)
Cumulative probability: P(X > k) = 1 - P(X <= k)

Theorems

Uniform Distribution Theorem

Suitable Grade Level

Grades 11-12