A psychologist is planning the study on effect of motivation on performance of attention task. In this task, participants try to estimate target letters in the stream of letters passing by at the rapid rate. The researcher knows from long experience that, under ordinary experimental conditions, the population of students who participate in this task determine mean of 71 of the key letters, the standard deviation is 10, and that the distribution is approximately normal. The psychologist predicts that, if the participant is paid a dollar for each letter identified correctly, that the number correctly identified will increase to 74. The psychologist plans to test 20 participants under these conditions, using the .05 level.
What is the probability of making a Type II error in this study?