Yahoo 知識+ 將於 2021 年 5 月 4 日 (美國東岸時間) 停止服務。從 2021 年 4 月 20 日 (美國東岸時間) 起,Yahoo 知識+ 網站將轉為僅限瀏覽模式。其他 Yahoo 資產或服務,或你的 Yahoo 帳戶將不會有任何變更。你可以在此服務中心網頁進一步了解 Yahoo 知識+ 停止服務的事宜,以及了解如何下載你的資料。

Introduction to Probability

Please to solve the following questions:

1. A positive integer lessthan 21 is chosen at random. What is the probability

that it is a multiple of 3?

2. Which of the following numbers can represent the probability of an event?

a. 3.1415/2 b. 1/3.1415 c. 1/2^1

3.A card is drawn at random from a pack of well-shuffled playing cards. What

is the probability of getting a Jack or a spade?

4.If two dice are rolled, the probability of getting a sum divisible by 4 is

5.A series of literature books contains 4 volumes, and they are arranged on a bookshelf at random. Whant is the probability that the first and the last volume are placed at both ends?

1 個解答

  • TamTam
    Lv 7
    1 十年前


    P(multiple of 3)

    =P(getting 3,6,9,12,15,18)




    1/3.1415 and 1/2^1 can represent a probability of event.

    (The values of above numbers are between 0 and 1)


    P(Jack or spade)

    =P(spade)+P(Jack)-P(spade Jack)





    P(divisible by 4)

    =P(get 4)+P(get 8)+P(get 12)

    =P(get (1,3)or(2,2)or(3,1))+P(get (2,6)or(3,5)or(4,4)or(5,3)or(6,2))+P(get(6,6))





    P(first, last volume are at both ends)

    =P(first volume at end A, then last volume at end B)+P(first volume at end B then last volume at end A)