注目の話題: わたしが悪いですか？; ホームランボールは小さな子供に譲るべきなの？？; 友人に裏切られ、どう対応して良いのか分かりません。

Science,English,and math Ⅱ

No.156　18/02/18 20:37
燻し銀三 ( 50代 ♂ Oe38xe ) あ+あ-

【The probability of each ball.】

《As to the number of each case,we can count it easily as long as we make a list.》

As to the question,if making a list,we can see its whole image and then we can understand what happens clearly.

As there are 4 white balls,we number each of them,W1,W2,W3,W4,and number each of red balls,R1,R2.R3. When putting back the ball,there are 49 combinations,W1,W1・W1,W2・W1,W3・W1,W4・W1,R1・W1,R2・W1,R3…then the first one is W2 and its combination is repeated.

I've said that as long as we make a list,we can understand easily,but I can't do it here,so I'm forced to omit it. I'm sorry for it.

As a result the combination of both of them are white balls are 16,so the probability is sixteen-49ths. It's the answer for the 1.

The combination of both of them are red balls are 9,so the probability is nine-49ths. It's the answer for the 2.

The combination that first one is a white ball and second one is a red ball are 12,so the probability is twelve-49ths. It's the answer…