The calculation process is as follows:

1, Event A and Event B are independent events, not mutually exclusive events, and cannot be added directly. We have to subtract their overlapping parts, that is, the probability of both success, because adding them up will count twice.

2, namely: p (a+b) = p (a)+p (b)-p (ab) = 0.5+0.5-0.5 * 0.5 = 0.75.

3. So 50% is 75%.

Extended data:

Superposition multiplication

For example, if you throw a coin, the probability is 1/2, then the probability of throwing it twice is 1/4, the probability of throwing it three times is 1/8, and so on. Mathematically, this is called multiplication theorem, that is, multiple events occur at the same time. If we prepare two things by multiplication, we can calculate the probability that both things will fail. Multiplying two things by 70% is 49%, and then the probability of success is 5 1%. If you prepare three pieces, multiply them by 70%, and the probability of failure of all three pieces is 34%, so the probability of success is 66%.