A seller has two weights, one of 1 kg and other of 2 kg. The weight of 1 kg is accurate while that of 2 kg actually measures 2.5 kg. He sold 20 kg of goods using 1 kg weight and actual 40 kg of goods(goods whose weight actually measures 40kg on proper weight) using 2 kg weight at cost price. How much loss did he face?
1
20%
2
33.33%
3
13.33%
4
18%
5
16.67%