In control replication, cells are replicated over a period of two days. Not until mitosis is completed can freshly synthesized DNA be replicated again. Two control mechanisms have been identified one positive and one negative. Suppose that a replication is observed in three cells. Let A denote the event that all cells are identified as positive and let B denote the event that all cells are negative. Describe the sample space graphically and display each of the following events:

(a) A

(b)

(c) 40B

(d) AUB