If the sprinkler takes 20 seconds to cross the garden, and it crosses the garden 150 times, the total number of seconds it took can be calculated by multiplying 20 and 150. You get 3000 seconds, but you need to convert that to minutes to tell if it will take more or less than an hour. So divide 3000 by 60 (the number of seconds in 1 minute). Your answer is 50 minutes. And since 1 hour is 60 minutes, it doesn't take more than an hour to cross the garden 150 times.
