I am completing an assignment for Statistics. I understood every question's instruction until this question:

The qexp() function in R allows you to enter a probability, and it will tell you the criterion value ("cutoff point") that corresponds to that probability value (e.g., if you enter .05 it tells you the cutoff point below which 5% of the values in the distribution fall).

What value ofxwould be the criterion value (cut-off point) for the top 5% of time intervals (Round to 3 decimal places, and include the units of measurement)?

The information that we are using to go along with this question:

Information

The exponential distribution is a continuous distribution.The main R functions that we will use for the exponential distribution are pexp() and qexp().Here is an example of the pexp() function.Leaves are falling from a tree at a rate of 10 leaves per minute.The rate is 10, or we can say that lambda = 10 (meaning 10 leaves fall per minute).The leaves do not fall like clockwork, so the time between leaves falling varies.If the time between leaves falling can be modeled with an exponential distribution, then the probability that the time between leaves falling will be less than 5 seconds (which is 5/60 of a minute) would be:

(note: this is an explanation of how pexp() works, you will answer a different question below)

pexp(5/60, rate=10)

which is about 0.565 (meaning that the probability is a bit higher than 50% that the next time-span between leaves falling will be less than 5 seconds).

For tasks 7-12,assume that the time interval between customers entering your store can be modeled using anexponential distribution. You know that you have an average of 4customers per minute, so therateis 4, or you can say that lambda = 4according to Yakir (2011, p. 79-80).

It is easiest to keep everything in the original units of measurement (minutes), but you can also translate that to seconds because a rate of "4 customers per minute" is the same as "4 customer per 60 seconds," and you can divide each number by 4 to get a rate of "1 customer per 15 seconds" or a rate of "1/15 customers per second."

The qexp function in R is qexp(p, rate). From the information above, I know that the rate is 4. To find the top 5% of time intervals using this function am I supposed to enter qexp(0.05, rate = 4) or something else?