數學題(Combination) 10分

Question

圖片參考：http://imgcld.yimg.com/8/n/HA00145646/o/7011121200...

ans: c: 364, d: 84 e: 371

請解釋以上問題

之後還有一連串combination問題希望各位回答或且比意見,感激不盡

Answer 1

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a) If anchovies cannot be selected, we still have 14 toppings to choose 3 randomly from them

So no. of combinations = 14C3 = 364

b) Excluding the vegetables, we still have 9 toppings to choose 3 randomly from them

So no. of combinations = 9C3 = 84

c) When there's no limitation, a total of 15C3 = 455 different combinations can be made.

So no. of 3-topping pizzas with at least one vegetable is 455 - 84 = 371

Source(s): 原創答案