how does it come up with the number N(d1)=0.522

- Consider a call on a NDP stock with current price $49, strike price $50, the risk-free rate 5%, time to maturity 20 weeks, volatility 20%. Calculate the delta and explain how to hedge this position d1=0.20.3846ln(5049)+(0.05+20.22)0.3846=0.0542 Delta is N(d1)=0.522. When the stock price changes by S, the option price changes by 0.522S