Running 320m in 56 seconds?

well i was bored so i went in the gym at school and a gym class was running they had to run 2 laps around the gym which is 160m. at least i think it is because 10 laps around it is a mile so 1 would be 160m. i ran it with them so thats 320m i ran it in 56 seconds is this good? plus i came in there just after eating lunch, i ate a pizza, carton of milk, and a small square cookie, i was also wearing jeans, i had big wool socks on, there was an iphone in my pocket, and my shoes are getting old so they were kinda falling off when i was running. So that probably means if i didnt have lunch and went in there normally and had better shoes and shorts on im guessing about 50 seconds or something right? do you know what my predicted 400m time would be? ps i beat everyone too it was so cool lol