Over the [1st, 2nd, 3rd, 4th] months, the game Extinguish the Fiery Chicken had [30,000, 20,000, 15,000, 20,000] users become inactive out of a MAU of [90,000, 120,000, 110,000, 100,000]. What was the churn of the second month? 20,000/120,000 = 16.67%