单选题 If the probability of an event is 0.20, what are the odds against the event occurring?

A、

A. Four to one.
B、

B. One to four.
C、

C. Five to one.

【正确答案】 A

【答案解析】The answer can be determined by dividing the probability of the event by the probability that it will not occur: (1/5)/(4/5)=1 to 4. The probability against the event occurring is four to one, i.e. in five occurrences of the event, it is expected that it will occur once and not occur four times.