How much damage the turrets exactly do?

So i was at level 8 against a fiora. you know. she does so much damage that she doesn't care about turrets as she will kill oyu quick. she dove me at level 8. she has 1 item. i stunned her. and then I was attacking her. me and the turret for 3 seconds before I died and she walked out hte turret range with 1/3 of her health. the turret was doing like 5% of her health per hit. this is stupid