Witches at a coffee shop

[I got this puzzle from Alex Pintilie.]

Two witches each makes a nightly visit to an all-night coffee shop. Each arrives at a random time between 0:00 and 1:00. Each one of them stays for exactly 15 minutes. On any one given night, what is the probability that the witches will meet at the coffee shop?

©2020-2023 K.R.M. Leino - Split Template by One Page Love