Suppose that you flip a coin 40 times and count the number of heads. 1.1. What is the distribution of the number of heads assuming the coin is fair

You would get 20 heads and 20 tails.

Explanation: Assuming that the coin is fair which you said it is, then you can also assume that there’s a 1/2 probability of getting heads each time you flip it and tails each time you flip it. So since you flipped it 40 times, you would assume to get heads 20 times and tails 20 times.