On probability

1/33。 Classmate A was drawn for cleaning three times in a row, and the probability that Classmate A was drawn for cleaning for the fourth time was 1/33 (unrelated to the previous three times), so the probability that Classmate A was drawn for cleaning for four times in a row was 1/33.

Classmate A was pumped for cleaning three times in a row. If the probability that classmate A is drawn for cleaning for four consecutive times is 3/4 (or 2/3), the prerequisite is:

Prepare 4 labels, 3 with color, 1 without color. Let classmate A draw lots by himself, sweep the floor with color, and do not sweep the floor without color, then the probability of sweeping the floor by lottery for the fourth time is 3/4 (that is, the probability of sweeping the floor for four consecutive times is 3/4).

(Or prepare 3 labels, 2 with color, 1 without color. Let classmate A draw lots by himself, sweep the floor with color, and do not sweep the floor without color, then the probability of sweeping the floor by lottery for the fourth time is 2/3 (that is, the probability of sweeping the floor for four consecutive times is 2/3). )