3 people should be met to be certain that you have met two people of same nationality. So, the answer is 3 people.
Step-by-step explanation:
Total people in a conference= 20 canadians+ 20 norwegians = 40 people.
The First person you meet out of 40 may be <u>either 1 Canadian or 1 Norwegian.</u>
If Canadian, then second person may be Norwegian or Canadian.
If Norwegian, then second person may be Canadian or Norwegian.
So, <u>By the end of two persons</u>: there may be the cases as
<u>case 1:</u> 1 Norwegian+ 1 Canadian and vice versa
(or)
<u>case 2:</u> Two Canadians
(or)
<u>case 3:</u> Two Norwegians
Now, the case 1 does not satisfies the condition given in the question
So, the <u>third person</u> as the possibility of being either Norwegian or Canadian which satisfies the given condition in the question that you meet two people of same nationality.