Math Problem Statement

The time in days between breakdowns of a machine is exponentially distributed with the parameter lambda = 0.2 What is the expected time and standard deviation of the time between machine breakdowns?

Solution

The exponential distribution has the following key properties for a given rate parameter λ\lambda:

  1. Expected Value (Mean): E(X)=1λE(X) = \frac{1}{\lambda}

  2. Standard Deviation: σ=1λ\sigma = \frac{1}{\lambda}

Given λ=0.2\lambda = 0.2, let's calculate these values:

1. Expected Time Between Breakdowns:

E(X)=1λ=10.2=5daysE(X) = \frac{1}{\lambda} = \frac{1}{0.2} = 5 \, \text{days}

2. Standard Deviation of Time Between Breakdowns:

σ=1λ=10.2=5days\sigma = \frac{1}{\lambda} = \frac{1}{0.2} = 5 \, \text{days}

Final Answer:

  • Expected Time: 5days5 \, \text{days}
  • Standard Deviation: 5days5 \, \text{days}

Would you like more details or have any questions?

Here are 5 related questions you might explore:

  1. How is the exponential distribution used in reliability analysis?
  2. What is the probability that the machine breaks down within 3 days?
  3. What is the cumulative distribution function (CDF) of this exponential distribution?
  4. How can this information be used to plan maintenance schedules?
  5. What is the memoryless property of the exponential distribution?

Tip: For exponentially distributed events, the mean and standard deviation are always the same!

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Math Problem Analysis

Mathematical Concepts

Probability
Exponential Distribution
Expected Value
Standard Deviation

Formulas

E(X) = 1 / λ
σ = 1 / λ

Theorems

Properties of the Exponential Distribution

Suitable Grade Level

Grades 11-12