A researcher was convinced that his research hypothesis was true and extra-sensory perception (ESP) is real. He was determined to repeat his ESP study until he finds it. He ran a total of 80 experiments. His colleague, who does not believe in ESP, pointed out that with his alpha set to alpha = 0.05, he is bound to likely 'find' ESP in at least one of his 80 experiments. In how many experiments, out of the 80, would he be expected to reject the null hypothesis, even if it was true?