Mathematics for IGCSE & O level - Probability (Section 5 - No. 28)
A survey showed that 40% of people prefer coffee and 60% prefer tea. If a person is selected at random, what is the probability they prefer either coffee or tea?
24%
40%
60%
100%
説明
Since preferences are mutually exclusive (you either prefer coffee or tea, assuming there are no other choices). The probability of either is 40% + 60% = 100%.