I am confused by the number of put options calculation in this question. Why use N(-d1) instead of N(d1)? my understanding is that since d1 is less than o, we shall use 0.5-data, so the N(d1) shall be 0.5-0.0219=0.4781, so the number of put options needed shall be : 200,000/(0.4781X1,000). am I wrong? why? pls advise. thanks