Javascript Math.pow() returning Uncaught TypeError: Cannot read property '0' of undefined

I can't seem to figure out why this:

Populations[0] = Math.round(Math.pow((Populations[0] * Math.E), (popGrowth * 5)));
Populations[1] = Math.round(Math.pow((Populations[1] * Math.E), (popGrowth * 5)));
Populations[2] = Math.round(Math.pow((Populations[2] * Math.E), (popGrowth * 5)));

returns this:

Uncaught TypeError: Cannot read property '0' of undefined

JSFiddle:http://ift.tt/1MYsAut

via Chebli Mohamed