Jerry has to walk to the sink/recycling bin 28 cans / 4 cans per trip = <<28/4=7>>7 trips
The round trip takes 10 seconds per way * 2 ways = <<10*2=20>>20 seconds
Counting the time he spent pouring out the cans and the time the round trip took, he spent 20 seconds per trip + 30 seconds per trip = <<20+30=50>>50 seconds per trip
With 7 round trips, he spent 50 seconds per trip * 7 trips = <<50*7=350>>350 seconds
#### 350