There are many possible ways to achieve this. One way is to store the strings in an array, and then index into that array using x.
x = 1; % Will also work for x==2 or x==3, giving the different strings
temperatureStr = ["mean", "minimum", "maximum"];
figure
scatter(rand(5,1),rand(5,1))
title(sprintf("Daily %s temperature",temperatureStr(x)))
If you share some broader context of your code, I expect there is a better way to track this info, because there is likely some redundancy in how you are using this indexing..
