Answer: [tex]f(t)=3.5e^{-3.5 t}\text{ for }t>0[/tex]
Step-by-step explanation:
The probability density function with exponential random variable T(t>0) with mean [tex]\lambda[/tex] is given by :-
[tex]f(t)=\lambda e^{-\lambda t}\text{ for }t>0[/tex]
Given : The time it takes to ring up a customer at the grocery store follows an exponential distribution with a mean of 3.5 minutes.
i.e. [tex]\lambda=3.5[/tex]
Then , the probability density function for the time it takes to ring up a customer is :
[tex]f(t)=3.5e^{-3.5 t}\text{ for }t>0[/tex]
