1.A certain area is located at the confluence of two rivers A and B. When either river

reaches the flood level, the area is inundated; the probability of river A reaching the

flood level is 0.1, the probability of river B reaching the flood level is 0.2, and the

chance of river B reaching the flood level when river A reaches the flood level is

known to be 0.4. Please answer the following questions.

(1) Floods occur in both rivers A and B.

(2) Only river A floods.

(3) Only river B floods.

(4) Flooding of either river A or river B.

(5) No flooding in both river A and river B.

Please answer clearly