考场上N（d1),N(d2)怎么求？

问题如下：

A European put option has the following characteristics: S0= $50; X = $45; r = 5%; T= 1 year; and σ = 25%. Which of the following is closest to the value of the put?

选项：

A.

$1.88.

B.

$3.28.

C.

$9.06.

D.

$10.39.

解释：

S0= $50; X = $45; r = 5%; T = 1 year; and σ = 25%.

d2= 0.74644 – 0.25 = 0.49644

from the cumulative normal table:

N(–d1) = 0.2266

N(–d2) = 0.3085*

p = 45e^[–0.05(1)]*(0.3085) – 50(0.2266) = 1.88