This is a question in my 5lb book of practice questions:
The probability of rain in Greg's town on Tuesday is 0.3. The probability that Greg's teacher will give him a pop quiz on Tuesday is 0.2. The events occur independently of each other.
what is the probability that either or both events occur?
the answer is 0.3 + 0.2 - (0.3)(0.2) = 0.44 but I don't understand why the probability of both events occurring is subtracted because the question asks for the occurrence of both evens to be included..