Swimming question..please help?

Is it possible to be able to swim 500 meters in 9 minutes by training for 1 month, twice a week, 2-3 hours per session? My abilities right now is swim 300 meters in 7 minutes. I haven't swam for a month, but i have been running..ALOT. I can run about 3-4 miles straight without stopping. When i did the 300 meters in 7 minutes, i could barely do 2 miles before stopping. My swim class is next week so i can test my swim times again. If possible, can someone tell me how much i should swim on each sessions? i got about 8 swim sessions before the 500 meter testing.