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高中第三册《概率》一章中新概念较多,教起来有些难讲清楚,现就其中几个易混概念,谈谈粗浅体会、供参考。一、事件与等可能事件在运用概率的古典定义计算概率时,有些学生由于区分不开“事件”与“等可能事件”而产生错误。如P_(168)。第五题,不少学生将一枚硬币连掷三次中可能出现“两枚正面一枚反面”(A)“两枚反面一枚正面”(B)“三枚正面”(C)“三枚反面”(D)这四个事件认为是等可能事件,因而得出P(A)=P(B)=1/4,这种分析是错误的,其原因在于混淆了事件与等可能事件的界限,错误地把A、B、C、D这四个可能发生的事件看成了等可能发生的事件。
There are many new concepts in the chapter “Probability” in the third book of high school. It is hard to explain clearly in teaching. Now we have a few confusable concepts to talk about and give a rough idea and reference. First, events and other possible events in the use of the probability of the classical definition of the probability of calculation, some students can not distinguish between the “event” and “likely events” and produce errors. Such as P_ (168). In the fifth question, many students may throw a coin three times in a row. There may be “two positives and one negative” (A) “two negatives and one positive” (B) “three positives” (C) "three The four events on the opposite side (D) are considered to be such possible events and therefore P(A) = P(B) = 1/4. This analysis is wrong because of the confusion of events and other possible events. The boundary mistakenly considers the four possible events A, B, C, and D as possible events.