Question

The average lifetime of a certain new cell phone is four years. The manufacturer will replace any cell phone failing within 3 years of the date of purchase. The lifetime of these cellphones is known to follow an exponential distribution. What is the decay rate (m)?

Answer 1

The decay rate 'm' is 0.25

Explanation:

As given,

Average Life time of New cell phone = 4 years

Lifetime of phone = L = ?

L is a random variable defining lifetime of a cell phone.

L∼ Exponential (m)

Mean of Exponential Distribution =
`(1)/(m)`

As, they follow exponential distribution, so to find decay rate , we simply can write it as :

`(1)/(m)` = 4

or

`m = (1)/(4)`

m=0.25

L∼ Exponential (0.25)

The decay rate is 0.25