exponential probability

[brisk flint]

During the Black Friday shopping, the time required to finalize an online purchase, in minutes, is a random variable here named Y.

Furthermore, Y is defined as Y = X + 1, with X being modeled by an exponential distribution with an average of 3.5 minutes.

What is the probability of an online purchase taking less than 3 minutes to be completed?

I am in doubt of how to work wit hthe Y=X+1. Does that just create another variable with an average of 4.5 mins?

[wooden gull]

yes Y has an expected value of 4.5, but do note that it won't have an exponential distribution

$\mathbb P(Y\leq y)=\mathbb P(X+1\leq y)=\mathbb P(X \leq y-1)$