Respuesta :
Answer and Step-by-step explanation: For an exponential distribution, the probability distribution function is:
f(x) = λ.[tex]e^{-\lambda.x}[/tex]
and the cumulative distribution function, which describes the probability distribution of a random variable X, is:
F(x) = 1 - [tex]e^{-\lambda.x}[/tex]
(a) Probability of distance at most 100m, with λ = 0.0143:
F(100) = 1 - [tex]e^{-0.0143.100}[/tex]
F(100) = 0.76
Probability of distance at most 200:
F(200) = 1 - [tex]e^{-0.0143.200}[/tex]
F(200) = 0.94
Probability of distance between 100 and 200:
F(100≤X≤200) = F(200) - F(100)
F(100≤X≤200) = 0.94 - 0.76
F(100≤X≤200) = 0.18
(b) The mean, E(X), of a probability distribution is calculated by:
E(X) = [tex]\frac{1}{\lambda}[/tex]
E(X) = [tex]\frac{1}{0.0143}[/tex]
E(X) = 69.93
The standard deviation is the square root of variance,V(X), which is calculated by:
σ = [tex]\sqrt{\frac{1}{\lambda^{2}} }[/tex]
σ = [tex]\sqrt{\frac{1}{0.0143^{2}} }[/tex]
σ = 69.93
Distance exceeds the mean distance by more than 2σ:
P(X > 69.93+2.69.93) = P(X > 209.79)
P(X > 209.79) = 1 - P(X≤209.79)
P(X > 209.79) = 1 - F(209.79)
P(X > 209.79) = 1 - (1 - [tex]e^{-0.0143*209.79}[/tex])
P(X > 209.79) = 0.0503
(c) Median is a point that divides the value in half. For a probability distribution:
P(X≤m) = 0.5
[tex]\int\limits^m_0 f({x}) \, dx[/tex] = 0.5
[tex]\int\limits^m_0 {\lambda.e^{-\lambda.x}} \, dx[/tex] = 0.5
[tex]\lambda.\frac{e^{-\lambda.x}}{-\lambda}[/tex] = [tex]-e^{-\lambda.x} + e^{0}[/tex]
[tex]1 - e^{-\lambda.m}[/tex] = 0.5
[tex]-e^{-\lambda.m}[/tex] = - 0.5
ln([tex]e^{-0.0143.m}[/tex]) = ln(0.5)
-0.0143.m = - 0.0693
m = 48.46
