The cost is "1" and the cardinality is "1".

Eighty percent, or 0.8 copies, is priced at 1+30% = 1.3, so the total selling price of this part is 0.8× 1.3 = 1.04.

The remaining 20%, that is, the price of 0.2 part is half of 65438 +0.3 = 0.65, so the price of this part is 0.2 × 0.65 = 0. 13.

The total selling price is1.04+0.13 =1.17.

The yield is (1.17-1)/1=17%.