The question asks for a 60day call option value using the binomial tree.

The problem is that they only give in the data : Risk-free = 3%.

In the calculation of the risk-free probabilities, I used Pi(u) = (1+r-d)/(u-d) with r = 0,03

Guess what ? I was supposed to use : 0,03^(60/365) !

I understand that we must use the one period rate, but in this case there was no indication. Should we assume the rate given is always 1 year ? In the EOCs it is not the case (at least they give more precisions)