What is the delta of a short position in 100 European put options on a nondividend-paying stock?

The options mature in 91 days. The current stock price is $40 per share, the exercise price of the options is $40, the risk-free interest rate is 8% per annum, and the volatility is 30% per annum. What investment is required for a delta-hedged portfolio?

What is your overnight profit if the stock price tomorrow is $39? What if it is $40.50?