title: Algorithm to select 1 of 2 Items Based on Probability
body: <p>I'm coding a project that generates two arrays containing data. One array contains data for a specific country and the other contains data for all countries.</p>
  
  <p>For example, if a user from the US makes a request, we will generate two arrays with data. One with data only for the US and the other with data for worldwide, including the US. I want to give the US array a 60% chance of being selected if the visitor is from the US. That means the other array will have a 40% chance of being selected.</p>
  
  <p>How does one code this??</p>