If john's dog slept 3 hours and snored every 1/3 of an hour, how many times did he snore

Per hour, he snores 3 times per hour since he snores once every 20 minutes. In 3 hours, there are 180 minutes, so 180/20 = 9. The dog snores 9 times in 3 hours.

Dog sleep= 3hrs
snore 1/3 of one hour
snore=1/3h=1/3×60=20 mins
3hrs= 20×3=60mins=1hrs