In baseball, a pitcher's earned-run average (the average number of runs given up every 9 innings, or 1 game) is given by
E = 9 ∙
,
where n is the number of earned runs allowed and i is the number of innings pitched. Suppose we fix the number of earned runs allowed at 3 and let i vary.
◦ 9
◦ 0
◦ 3
◦ ∞