Refer to Exercise 5.26. Assume we have just discovered that, because of time constraints, each subject can see only two of the four classes. The rest of the experiment will remain the same, however....

Refer to Exercise 5.26. Assume we have just discovered that, because of time constraints, each subject can see only two of the four classes. The rest of the experiment will remain the same, however. Now how many subjects do we need? (Warning: Do not actually try to run an experiment like this unless you are sure you know how you will analyze the data.)