B.Com.
174 Points
Joined August 2008
for calculating d1 you need to use the formula
[ln(Spot/Strike)+((r+variance/2)*time)]/std.dev*sqr root of time
Normally the ln() values will be given as a part of question. So normally you need not worry about it.
The standard normal distribution table gives cumulative probabilities i.e. if the value of d1 is .3 then the table gives the probability of observing values less than and upto .3.
The rules for using standard norm dist table are as under:
prob(positive d1) - read off the value from table. use linear interpolation for values lower than .001
prob(negative d1) - convert it into 1 - prob(positive d1) and use above rule.
Same applies for d2