明天的表现和今天有什么实际关系呢

问题如下：

According to the above table, which of the following statements is the most correct?

选项：

A.

The total probability of having next day's good performance is 0.42.

B.

The total probability of having next day's good performance is 0.021.

C.

The total probability of having next day's good performance is 1.00.

解释：

A is correct

The total probability of having next day's performance is =$\left(0.4\right)\times \left(0.7\right)+\left(0.2\right)\times \left(0.3\right)+\left(0.4\right)\times \left(0.2\right)=0.42$