问一道曼哈顿的题

Allen_Ssh · 发表于 2017-6-24 22:19:53

A farmer has an apple orchard consisting of Fuji and Gala apple trees. Due to high winds this year 10% of his trees cross pollinated, creating trees that are part Fuji and part Gala. The number of his trees that are pure Fuji plus the number that are part Fuji and part Gala totals 187, while 3/4 of all his trees are pure Fuji. How many of his trees are pure Gala? 答案解析为：This problem can be solved using a set of four equations with four unknowns. The fourth variable will represent the total number of apple trees. We'll add two equations together to solve for the number of Gala apples relatively simply:

Let F = the number of Fuji trees
Let C = the number of cross pollinated trees
Let G = the number of Gala trees
Let T = the total number of trees

Equation (1): By definition, F + C + G = T

Equation (2): The pure Fuji trees plus the cross pollinated trees total 187, so F + C = 187

Equation (3): 75% of his trees are Fuji, so F = 0.75TEquation (4): 10% of his trees cross pollinated, so C = 0.1T

We can add these two equations together to show that 85% of the trees are Fuji or cross pollinated: F + C = 0.85T

Substituting from Equation (2), we get 0.85T = 187, or T = 220

Plugging back into the original "total" equation, we get the following:

F + C + G = T
(F + C) + G = 220
187 + G = 220
G = 33

So the farmer has 33 trees that are pure Gala.

标红处为疑问点，我觉得这里C=0.1T存在问题，因为这10%的交叉授粉应当基于的主体是之前的两个pure的，而不是之后三个相加的，所以这里应该是(T-C)*10%=C，不知道大家怎么看？

Allen_Ssh · 发表于 2017-6-25 18:36:49

有人吗？

fxxxfxxx · 发表于 2017-6-26 09:56:40

是 F ＋ C ＋ G ＝ T

Cross pollinate不会Create trees from nowhere, 是change the apple from Fuji or Gala to crossbreed.

Allen_Ssh · 发表于 2017-6-26 19:14:24

fxxxfxxx 发表于 2017-6-26 09:56
是 F ＋ C ＋ G ＝ T

Cross pollinate不会Create trees from nowhere, 是change the apple from Fuji or G ...

了解了，感谢！

问一道曼哈顿的题

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