M&S !

akjerryho

COUNTING & PROBABILITY


David and Lucy visit a restaurant for a three-course meal. On the menu there are 4 starters, 5 main courses and 3 sweets. David and Lucy each order a starter, a main course and a sweet.
(a) Calculate the number of ways in which David may choose his three-course meal.
(b) Suppose that David and Lucy choose different dishes from each other.
     (i)  Find the number of possible combinations of starters.
     (ii) Calculate the number of possible combinations of 6 dishes for both meals.
(c) Suppose instead that David and Lucy choose their dishes independently.
     (i)  Write down the probability that they choose the same main course.
     (ii) Find the probability that they choose different dishes from each other for every course.


其實重點系, 我吾明b(i)問咩
另外都希望各位高手留低自己既答案, 我都吾系好肯定其他岩 Orz

Naozumi

(a) 4 x 5 x 3 = 60

(b)(i) 4 x 3 = 12 我估意思係指兩個人所點的菜均不同
     (ii) (4 x 5 x 3) x (3 x 4 x 2) = 1440

(c)(i) 1 x 1/5 = 1/5
     (ii) (1 x 3/4)  x (1 x 4/5) x (1 x 2/3)

akjerryho

原帖由 Naozumi 於 10-10-18 08:05 PM 發表
(a) 4 x 5 x 3 = 60

(b)(i) 4 x 3 = 12 我估意思係指兩個人所點的菜均不同
     (ii) (4 x 5 x 3) x (3 x 4 x 2) = 1440

(c)(i) 1 x 1/5 = 1/5
     (ii) (1 x 3/4)  x (1 x 4/5) x (1 x 2/3)

啊謝了 !
睇黎系我諗得太複雜= =