Two friends are opening a coffee shop. As they write their business plan, they research the amount of debt similar businesses can have in the first two years of opening. It is known that 72 % of coffee shops have a debt of over $ 50 , 000 within the first two years of opening. If a random sample of 36 coffee shops is obtained, what is the probability that more than half of them had debt of over $ 50 , 000 within the first two years of opening?