Maude - 225 albums, 135 heavy metal, 135/225 = 0.6 = probability of listening to heavy metal
Claude - 420 albums, 270 heavy metal, 270/420 = 0.64 (2 DP) = probability of listening to heavy metal
Assuming the albums are picked randomly ... Claude has the highest probability of listening to heavy metal at 0.64 (2 DP), appose to Maude whose probability is less at 0.6.