Answer: 0.9765
Explanation:
The cumulative distribution function for exponential distribution for random variable x is given by :-
, where
is the mean of the distribution .
Given : On average, 5 customers arrive at the drive-up window of a fast-food restaurant every 4 minutes during the lunch hour.
Then
Now, the probability that the next customer will arrive within three minutes :-
Hence, the probability that the next customer will arrive within three minutes = 0.9765