Suppose the lady tasting tea is asked to identify which of 20 cups of tea had the milk poured first. Again, assume the cups of tea for which the milk was poured before the tea are chosen at random by tossing a fair coin.
How many cups would the lady have to correctly identify before we would consider the result of the experiment statistically significant?
If $X$ is the number of cups of tea she identifies correctly, make a plot of $P(X \ge x)$ versus $x$ for $x = 0, 1, 2, \ldots, 20$, under the assumption she is guessing.