Question

Historical evidence indicates that times between fatal accidents on scheduled American domestic passenger flights have an approximately exponential distribution. Assume that the mean time between accidents is 43 days. What is the variance of the times between accidents

Answer 1

The variance of the times between accidents is of 1849 days squared.

Explanation:

Exponential distribution:

The exponential probability distribution, with mean m, is described by the following equation:

`f(x) = \mu e^(-\mu x)`

In which
`\mu = (1)/(m)` is the decay parameter.

The variance of the exponential distribution is:

`Var = (1)/(\mu^2)`

Assume that the mean time between accidents is 43 days.

This means that
`m = 43, \mu = (1)/(43)`

What is the variance of the times between accidents?

`Var = (1)/(((1)/(43))^2) = 43^2 = 1849`

The variance of the times between accidents is of 1849 days squared.