Textbook ExpertVerified Tutor
17 Nov 2021
Given information
Use the following information to answer the next three exercises. The average lifetime of a certain new cell phone is three years. The manufacturer will replace any cell phone failing within two years of the date of purchase. The lifetime of these cell phones is known to follow an exponential distribution.
Suppose that the longevity of a light bulb is exponential with a mean lifetime of eight years.
Step-by-step explanation
Step 1.
As given in the problem that the average lifetime of a certain new cell phone is three years. And the manufacturer will replace any cell phone failing within two years of the date of purchase. The lifetime of these cell phones is known to follow an exponential distribution.
Therefore, the random variable is given by,
.
Where is the mean.
Now, the decay rate is given by
The cumulative distribution function for the exponential distribution is given as follows:
The required probability can be written as and using the complimentary law of probability,
Using the memoryless exponential distribution,
Therefore, the probability is given by
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