In: Statistics and Probability
An exponential distribution is formed by the time it takes for a person to choose a birthday gift. The average time it takes for a person to choose a birthday gift is 41 minutes. Given that it has already taken 24 minutes for a person to choose a birthday gift,what is the probability that it will take more than an additional 34 minutes?
Let X is the random variable denoting the time it takes for that person to choose a birthday gift.
Then by the problem we have,
, is the parameter of the distribution.
Therefore, the p.d.f. of X is given by,
,
, otherwise
and the c.d.f. of X is given by,
,
, otherwise
Since, the average time it takes for a person to choose a birthday gift is 41 minutes, therefore, we have
i.e.
Now, given that it has already taken 24 minutes for that person to choose a birthday gift, the probability that it will take more than an additional 34 minutes i.e. total (34 + 24) = 58 minutes
= 0.4364 (rounded to 4 decimal places)
Answer: Given that it has already taken 24 minutes for that person to choose a birthday gift, the probability that it will take more than an additional 34 minutes is 0.4364.