A basketball hoop is 18 inches (45.7 cm) in diameter.  This hoop is the target for a 9 inch basketball, 50% of the hoop diameter.

A golf cup is 4¼" inches (10.8 cm) in diameter. This cup is the target for a 1.68" (4.2 cm) diameter golf ball, 39.5% of the cup diameter.

When I first calculated these 50% and 39.5% ball to hole ratios, I was tempted to continue comparing basketball to golf. It didn't take long for me to realize that that would be silly.

There are other sports that have something like a ball diameter to goal diameter ratio, (billiards, hockey, soccer, croquet, pinball, tlachtli, field hockey, polo, throwing a football through a hanging tire) but the comparison breaks down if I tried to include these.