To be honest without more information or some assumptions this question

cannot be answered.

If we assume that the closing prices have a normal distribution then we

would be looking at the t table with 35 degrees of freedom (as 35 is a small

sample for these purposes). But without this assumption all we can say

nothing.

Now it might be that you are expected to make some assumtion but without

seeing your notes we don't know if you are supposed to treat 36 as a large

number and so use the z table, or assume the closing prices are normal, but

36 is small and so use the t table.

RonL