Law of Large Numbers
A famous study by Amos Tversky and Nobel laureate Daniel Kahneman asked people to consider two hospitals. Hospital A is small and has 15 babies born per day. Hospital B has 45 babies born each day.
Over one year, each hospital recorded the number of days that it had more than 60% girls born. Assuming that 50% of all babies are girls, which hospital had the most such days?
Or do you think both will have about the same number of days with more than 60% girls born? Answer, and explain.
(Source: Amos Tversky. 2004. Preference, Belief, and Similarity: Selected Writings, ed. Eldar Shafir. Cambridge, Mass.: MIT Press, p. 205)