Is 9 suitable for this range?

Sale 1

[No OP Trade] Sold for P. Fetti Gonz

X = 11*0.9

X = 10

Gonz http://backpack.tf/item/388390984

Tam http://backpack.tf/item/1124831348

Mini for Gonz

http://backpack.tf/vote/id/56748a16dea9e9ec307f76e5 11 keys, using 11

Sale 2

http://backpack.tf/profiles/76561198065874329?time=1448611200&compare=1448524800 Sold for like 25 keys of sweets

Outlier

Sale 3

http://www.tf2outpost.com/trade/27469662 Sold for a key + 9 keys of pure garbage, again

B/O for Tam was 10.5

X = 1 + 9*0.9

X = 9

Trade + Garbage http://backpack.tf/profiles/76561198019146783?time=1448179200&compare=1450080000

Tam http://backpack.tf/item/1074825724

Sale 4

http://www.tf2outpost.com/trade/27426999 Sold for OF Glen

B/O for Bonnet was 12

Tam had no trade, presuming offered

X = 12

Glen http://backpack.tf/item/1483818693

Tam http://backpack.tf/item/1074825724

Trade http://backpack.tf/profiles/76561198072960996?time=1447574400&compare=1447747200

Mini for Glen

http://backpack.tf/vote/id/5674a630b98d88e128e94ae4 12 keys, using 12