[!!!急]數學_Probility_8－dkdqgav的部落格

標題:

[!!!急]數學_Probility_8

發問:

A box contains 156 rubber bands. There are 100 yellow rubber bands and the rest are green or red. The green ones are 3 times as many as the red ones.a) Find the number of green bands.b) Find the probability of getting a red band if a band is randomly chosen from the box. c) y red bands are added to the... 顯示更多 A box contains 156 rubber bands. There are 100 yellow rubber bands and the rest are green or red. The green ones are 3 times as many as the red ones. a) Find the number of green bands. b) Find the probability of getting a red band if a band is randomly chosen from the box. c) y red bands are added to the box. The probability of part b) becomes 10/81 . Find y. 更新: 我需要詳細板呀!!!!!!!!

最佳解答:

A box contains 156 rubber bands. There are 100 yellow rubber bands and the rest are green or red. The green ones are 3 times as many as the red ones. a) Find the number of green bands. Let x be the munber of the red ones. Then, the number of green ones are 3x. x+3x+100 = 156 4x = 56 x = 14 ∴the number of green bands are 14X3=42. b) Find the probability of getting a red band if a band is randomly chosen from the box. P(getting a red band) =14/156 =1/14 c) y red bands are added to the box. The probability of part b) becomes 10/81 . Find y. (14+y)/(156+y) = 10/81 1134+81y = 1560+10y 71y = 426 y = 6 2009-06-02 21:42:09 補充： 2b 係 7 / 78 打錯左 2009-06-02 21:43:30 補充： 2a. Let x be the munber of the red ones. 應該是Let x be the number of the red ones.

其他解答:

a) (１５６-１００) x ３/4 = ４２ b) (１５６-１００-４２)/１５６ = 7/78 c) (１５６-１００-４２+ y ) / (１５６+ y ) = １０/８１８１(１４+ y ) = １０(１５６+ y ) １１３４+８１y = １５６０ + １０y ７１y = １５６０ - １１３４ y = ６|||||a) 42 b) 7/78 c) 6 請問概率係咪串錯左?@@ 好似Probability至岩wor