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f5 maths!!!!!!!
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There are 2 white balls, 4green balls and 3 blue balls in a box. If three balls are drawn one after another with replacement, find the probability that all the balls have the same colour. 我知道有人答如下:P(all the balls have the same colour)=P(GGG)+P(WWW)+P(BBB)=64/729+(2/9)^3+(3/9)^3=11/81... 顯示更多 There are 2 white balls, 4green balls and 3 blue balls in a box. If three balls are drawn one after another with replacement, find the probability that all the balls have the same colour. 我知道有人答如下: P(all the balls have the same colour) =P(GGG)+P(WWW)+P(BBB) =64/729+(2/9)^3+(3/9)^3 =11/81 但我唔明點解可以WWW呢? only 2 white balls!!! 但11/81係岩.... 有時間請到我的發問,我仲有一條唔明....
最佳解答:
There are 2 white balls, 4green balls and 3 blue balls in a box. If three balls are drawn one after another with replacement, find the probability that all the balls have the same colour. 我知道有人答如下: P(all the balls have the same colour) =P(GGG)+P(WWW)+P(BBB) =64/729+(2/9)^3+(3/9)^3 =11/81 但我唔明點解可以WWW呢? only 2 white balls!!! 但11/81係岩.... 因為with replacement, 所以當第1 個是white , 就加番1 個white, 於是第2 個抽到white 既機會又係 2/9. 如是者, 第3 個抽到white 既機會又係 2/9. 結果, 2/9＊2/9＊2/9
其他解答:
條數係咪話 抽出後既ball放回個box度? 如果係既話,,, 同時抽出三個ball同一顏色既概率均如下: 第一次抽到G後再放回box,,第二次抽到又係g之後又放回box度,,第三次抽到G後又係放回box度,, 形成 P(GGG) 注意:同時抽出三粒ball既意思係 "第一次抽既係G,,第二次抽中又係G,,第三次抽中又係G" 至於點解可以P(WWW),,,這是因為你第一次抽一粒W出黎之後再放回BOX度,,然後再抽,,再放回BOX,,再抽,,, 但係個BOX度既BALL既總數依然不變,,所以W自然沒有少,,, 因為有可能3次都抽到G, 3次都抽到W, 3次都抽到B 所以我地會把佢地既概率全部 +晒佢 即 P(GGG or WWW or BBB)|||||with replacement ma .. white balls drawn are replaced with another white one
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