中考英语概率计算单选题50题

中考英语概率计算单选题50题
1. There is a lottery box with 10 tickets, and only 2 of them are winning tickets. If you randomly draw one ticket, the probability of getting a winning ticket is
A. 1/10
B. 1/5
C. 2/10
D. 2/5
答案：B。

本题考查简单概率计算。

总共有10 张票，其中2 张是中奖票，所以中奖概率是2÷10=1/5。

选项 A 计算错误，选项C 未化简，选项D 计算错误。

2. You toss a coin once. The probability of getting heads is
A. 0
B. 1/2
C. 1
D. 2
答案：B。

抛硬币只有正反两面，出现正面的概率是1÷2=1/2。

选项 A 表示不可能，不符合实际；选项C 表示一定，也不符合抛硬币的情况；选项D 错误。

3. In a box, there are 5 red balls and 15 blue balls. If you randomly pick one ball, the probability of getting a red ball is
A. 1/3
B. 1/4
C. 1/5
D. 1/20
答案：B。

总共有5 + 15 = 20 个球，其中红球5 个，所以摸到红球的概率是5÷20=1/4。

选项 A 计算错误，选项 C 未考虑总数，选项D 计算错误。

4. There are 20 students in a class. 8 of them are boys. If you randomly choose one student, the probability of choosing a girl is
A. 2/5
B. 3/5
C. 8/20
D. 12/20
答案：B。

总共有20 个学生，8 个是男生，那么女生有12 个，所以选到女生的概率是12÷20=3/5。

选项 A 计算错误，选项C 是男生的概率，选项D 未化简。

5. A bag contains 3 apples and 7 oranges. If you pick one fruit randomly, the probability of getting an apple is
A. 3/7
B. 3/10
C. 7/10
D. 7/3
答案：B。

总共有3 + 7 = 10 个水果，其中苹果3 个，所以拿到
苹果的概率是3÷10=3/10。

选项A 计算错误，选项C 是拿到橘子的概率，选项D 计算错误。

6. The probability of getting a head when flipping a coin is 0.5. If you flip the coin 10 times, what is the probability of getting exactly 5 heads?
A. 0.25
B. 0.20
C. 0.15
D. 0.10
答案：A。

本题考查二项分布概率计算。

每次抛硬币得到正面的概率为0.5，抛10 次，恰好得到5 次正面的概率可以通过二项分布公式计算：C(10, 5) * 0.5^5 * 0.5^5 = 0.25。

选项B、C、D 的计算结果均不正确。

7. A bag contains 5 red balls and 3 blue balls. If you randomly draw a ball twice without replacement, what is the probability of getting a red ball both times?
A. 25/56
B. 20/56
C. 15/56
D. 10/56
答案：A。

第一次抽到红球的概率为5/8，第二次在剩下的7 个球中抽到红球的概率为4/7，两次都抽到红球的概率为5/8 * 4/7 = 25/56。

选项B、C、D 的计算过程错误。

8. The probability of event A is 0.6 and the probability of event B is 0.4. If events A and B are independent, what is the probability of both A and B occurring?
A. 0.24
B. 0.16
C. 0.10
D. 0.04
答案：A。

因为A 和B 独立，所以两者同时发生的概率为0.6 * 0.4 = 0.24。

选项B、C、D 的乘积结果错误。

9. In a class, 60% of the students are boys. If 10 students are randomly selected, what is the probability that exactly 6 of them are boys?
A. 0.25
B. 0.20
C. 0.15
D. 0.10
答案：A。

这是一个二项分布问题。

概率为C(10, 6) * 0.6^6 * 0.4^4 ≈ 0.25。

选项B、C、D 的计算结果与正确计算不符。

10. A spinner is divided into 4 equal sections labeled 1, 2, 3, and 4. If you spin it twice, what is the probability of getting a 1 on the first spin and a 2 on the second spin?
A. 1/16
B. 1/8
C. 1/4
D. 1/2
答案：B。

第一次转到1 的概率为1/4，第二次转到2 的概率也为1/4，所以两次都满足的概率为1/4 * 1/4 = 1/8。

选项A、C、D 的计算错误。

11. In a football match, the probability of Team A winning is 0.6. What is the probability of Team A not winning?
A. 0.4
B. 0.5
C. 0.3
D. 0.7
答案：A。

本题考查概率的基本计算。

Team A 获胜的概率是0.6，那么不获胜的概率就是1 - 0.6 = 0.4 。

12. The weather forecast says there is a 70% chance of rain tomorrow. What is the chance of no rain tomorrow?
A. 30%
B. 40%
C. 50%
D. 60%
答案：A。

已知有70%的下雨概率，不下雨的概率就是100% - 70% = 30% 。

13. In a lottery, the probability of winning the first prize is 0.001. What
is the probability of not winning the first prize?
A. 0.999
B. 0.99
C. 0.9
D. 0.009
答案：A。

因为中奖概率是0.001 ，所以不中奖的概率就是1 - 0.001 = 0.999 。

14. The probability of a student passing an exam is 0.8. What is the probability of the student failing the exam?
A. 0.2
B. 0.3
C. 0.4
D. 0.1
答案：A。

通过考试的概率是0.8 ，那么不及格的概率就是1 - 0.8 = 0.2 。

15. At a basketball game, the probability of Team B scoring more than 100 points is 0.3. What is the probability of Team B scoring 100 points or less?
A. 0.7
B. 0.6
C. 0.5
D. 0.4
答案：A。

Team B 得分超过100 分的概率是0.3 ，那么得分100 分及以下的概率就是1 - 0.3 = 0.7 。

16. A survey was conducted on 100 students about their favorite subjects. 40 students chose Math, 30 chose Science, and 20 chose English. If a student is randomly chosen, what is the probability that they chose either Math or Science?
A. 70/100
B. 40/100
C. 30/100
D. 20/100
答案：A。

本题考查概率的计算。

喜欢数学的有40 人，喜欢科学的有30 人，所以喜欢数学或者科学的人数为40 + 30 = 70 人。

总人数为100 人，所以概率为70÷100 = 70/100。

17. In a class of 50 students, 25 have brown eyes and 15 have blue eyes. The rest have green eyes. If a student is randomly selected, what is the probability that they have either brown or blue eyes?
A. 40/50
B. 25/50
C. 15/50
D. 10/50
答案：A。

喜欢棕色眼睛的有25 人，喜欢蓝色眼睛的有15 人，所以喜欢棕色或者蓝色眼睛的人数为25 + 15 = 40 人。

总人数为50
人，所以概率为40÷50 = 40/50。

18. A box contains 10 red balls and 15 blue balls. If two balls are randomly drawn without replacement, what is the probability that both are red?
A. 10/25 × 9/24
B. 10/25 × 10/24
C. 15/25 × 14/24
D. 15/25 × 15/24
答案：A。

第一次抽到红球的概率是10÷25，第二次抽到红球的概率是9÷24，两次都抽到红球是两个概率相乘，即10/25 × 9/24 。

19. The grades of a class of 30 students are recorded. 12 students got A, 8 got B, and 10 got C. If a student is randomly chosen, what is the probability that they got either A or B?
A. 20/30
B. 12/30
C. 8/30
D. 10/30
答案：A。

得到 A 的有12 人，得到 B 的有8 人，所以得到A 或者B 的人数为12 + 8 = 20 人。

总人数为30 人，所以概率为20÷30 = 20/30 。

20. A bag has 5 apples and 3 oranges. Two fruits are randomly picked one after the other. What is the probability of getting an apple first and then
an orange?
A. 5/8 × 3/7
B. 5/8 × 3/8
C. 3/8 × 5/7
D. 3/8 × 2/7
答案：A。

第一次拿到苹果的概率是5÷8，此时剩下7 个水果，其中 3 个是橙子，所以第二次拿到橙子的概率是3÷7，两次概率相乘为5/8 × 3/7 。

21. A square has a side length of 4 units. A point is randomly chosen inside the square. What is the probability that the point is closer to the center of the square than to any of the sides?
A. 1/4
B. 1/2
C. 3/4
D. 1
答案：A。

本题考查正方形内点的位置与概率的关系。

正方形的面积为16 平方单位，以正方形中心为圆心，以边长一半 2 为半径的圆的面积为4π 平方单位。

点在圆内时满足条件，概率即为圆的面积除以正方形面积，4π÷16 = π/4 ≈ 1/4 。

22. A rectangle has length 6 units and width 4 units. A point is randomly chosen inside the rectangle. What is the probability that the point is within a distance of 1 unit from the rectangle's diagonal?
A. 1/12
B. 1/6
C. 1/4
D. 1/3
答案：B。

先求出矩形对角线的长度为2√13 单位。

以对角线为直径的圆的面积为13π 平方单位，矩形面积为24 平方单位。

点在圆内满足条件，概率为13π÷24 = 13π/24 ≈ 1/6 。

23. A circle has a radius of 5 units. A point is randomly chosen inside the circle. What is the probability that the point is within a distance of 2 units from the circumference of the circle?
A. 9/25
B. 4/25
C. 16/25
D. 3/5
答案：C。

圆的面积为25π 平方单位，以半径减去2 为半径的同心圆的面积为9π 平方单位。

点在两圆之间满足条件，概率为(25π - 9π)÷25π = 16/25 。

24. A triangle has sides of length 3 units, 4 units, and 5 units. A point is randomly chosen inside the triangle. What is the probability that the point is closer to the longest side than to the other two sides?
A. 1/2
B. 2/3
C. 3/4
D. 4/5
答案：A。

先求出三角形的面积为 6 平方单位。

以最长边为底边，作高，计算出高对应的三角形面积为 4 平方单位。

点在这个小三角形内满足条件，概率为4÷6 = 2/3 。

25. A regular hexagon has a side length of 2 units. A point is randomly chosen inside the hexagon. What is the probability that the point is within a distance of 1 unit from any of the vertices of the hexagon?
A. 1/6
B. 1/3
C. 1/2
D. 2/3
答案：B。

先求出正六边形的面积，然后计算以顶点为圆心，1 为半径的扇形面积，6 个扇形面积之和除以正六边形面积即为概率，约为1/3 。

26. There are 5 red balls and 3 blue balls in a box. If you randomly pick one ball without looking, the probability of getting a red ball is:
A. 3/8
B. 5/8
C. 3/5
D. 5/3
答案：B。

本题中，球的总数为8 个，其中红球有5 个，所以
随机抽取一个球是红球的概率为5÷8 = 5/8 。

27. A bag contains 2 apples and 3 oranges. If you choose one fruit randomly, the probability of getting an apple is:
A. 2/3
B. 2/5
C. 3/5
D. 3/2
答案：B。

水果总数为5 个，苹果有2 个，所以随机拿到苹果的概率是2÷5 = 2/5 。

28. In a class, there are 15 boys and 10 girls. If a student is randomly selected to be the monitor, the probability that it is a girl is:
A. 1/2
B. 2/5
C. 3/5
D. 1/3
答案：B。

学生总数为25 人，女生有10 人，所以随机选到女生当班长的概率为10÷25 = 2/5 。

29. There are 8 cats and 6 dogs in a pet store. If a pet is chosen at random, the probability of choosing a dog is:
A. 3/7
B. 4/7
C. 3/4
答案：A。

宠物总数为14 只，狗有6 只，所以随机选到狗的概率为6÷14 = 3/7 。

30. A box has 3 green marbles and 5 yellow marbles. If you pick one marble randomly, the probability of getting a green marble is:
A. 3/5
B. 3/8
C. 5/8
D. 5/3
答案：B。

marble 总数为8 个，绿色的有3 个，所以随机拿到绿色marble 的概率是3÷8 = 3/8 。

31. There are 5 red balls and 3 blue balls in a box. The probability of randomly picking a red ball is _____.
A. 3/8
B. 5/8
C. 3/5
D. 5/3
答案：B。

本题建立了简单的古典概率模型。

总球数为8 个，其中红球 5 个，所以随机抽取到红球的概率为红球个数除以总球数，即5÷8 = 5/8 。

32. A fair dice is rolled. The probability of getting an odd number is _____.
B. 1/3
C. 2/3
D. 1/6
答案：A。

骰子有6 个面，分别是1、2、3、4、5、6，其中奇数有1、3、5，共3 个。

所以得到奇数的概率为3÷6 = 1/2 。

33. There are 10 cards numbered from 1 to 10. If one card is randomly selected, the probability of getting a prime number is _____.
A. 2/5
B. 3/5
C. 4/5
D. 1/5
答案：B。

1 到10 中的质数有2、3、5、7，共4 个。

所以随机抽取一张得到质数的概率为4÷10 = 2/5 。

34. In a bag, there are 2 green marbles and 4 yellow marbles. The probability of picking a green marble at random is _____.
A. 1/3
B. 2/3
C. 1/2
D. 1/4
答案：A。

总共有6 个弹珠，其中绿色的有2 个，所以随机抽取到绿色弹珠的概率为2÷6 = 1/3 。

35. A spinner is divided into 8 equal sections, numbered 1 to 8. The probability of landing on a multiple of 3 is _____.
A. 1/4
B. 3/8
C. 1/2
D. 3/4
答案：B。

1 到8 中3 的倍数有3、6，共2 个。

所以指针落在3 的倍数的概率为2÷8 = 3/8 。

36. In a probability experiment, a coin is tossed 100 times. The number of heads is 45. What is the experimental probability of getting a head?
A. 0.45
B. 0.5
C. 0.55
D. 0.4
答案：A。

本题中，硬币共抛掷100 次，出现正面45 次，实验概率即为正面出现的次数除以总次数，45÷100 = 0.45。

37. A bag contains 5 red balls and 3 blue balls. If a ball is randomly drawn 50 times, and 25 times it is red. What is the experimental probability of drawing a red ball?
A. 0.5
B. 0.4
C. 0.6
D. 0.3
答案：A。

总抽取次数为50 次，抽到红球25 次，实验概率为25÷50 = 0.5 。

38. In a dice-throwing experiment, a dice is thrown 200 times. The number of times a 6 appears is 30. What is the experimental probability of getting a 6?
A. 0.15
B. 0.2
C. 0.25
D. 0.1
答案：A。

投掷200 次，出现6 的次数为30 次，实验概率为30÷200 = 0.15 。

39. A spinner is divided into 4 equal sections: red, blue, green, and yellow. It is spun 80 times, and the red section is landed on 20 times. What is the experimental probability of landing on the red section?
A. 0.25
B. 0.5
C. 0.2
D. 0.3
答案：C。

总共旋转80 次，红色区域出现20 次，实验概率为20÷80 = 0.25 。

40. In a card-drawing experiment, a deck of cards is shuffled and a card is randomly drawn 120 times. The number of times an ace is drawn is
10. What is the experimental probability of drawing an ace?
A. 0.083
B. 0.08
C. 0.09
D. 0.075
答案：A。

总抽取次数120 次，抽到A 牌10 次，实验概率为10÷120 ≈ 0.083 。

41. In the ancient game of dice, the chance of getting a six is _____.
A. one-sixth
B. one-fifth
C. one-fourth
D. one-third
答案：A。

在古代骰子游戏中，骰子有六个面，出现六的概率是六分之一。

42. The story of Pascal and Fermat's study of probability originated from _____.
A. a gambling game
B. a math competition
C. a scientific experiment
D. a history class
答案：A。

帕斯卡和费马对概率的研究源于一场赌博游戏。

43. In the legend of the Greek gods, the probability of Zeus appearing in a random event is _____.
A. very high
B. very low
C. half
D. impossible
答案：B。

在希腊众神的传说中，宙斯随机出现的概率非常低。

44. The famous mathematician Galileo also explored probability in his studies related to _____.
A. astronomy
B. physics
C. geometry
D. algebra
答案：B。

著名数学家伽利略在他与物理学相关的研究中也探索了概率。

45. The probability of finding a hidden treasure in a mysterious cave described in an old tale is _____.
A. very likely
B. unlikely
C. certain
D. impossible
答案：B。

在一个古老故事中描述的神秘洞穴里找到隐藏宝藏的概率不大。

46. The probability of getting a head when flipping a fair coin is ______.
A. 0
B. 1/2
C. 1
D. 2
答案：B。

本题考查概率的基本概念。

一枚公平硬币只有正反两面，出现正面的概率是1/2。

47. If the probability of event A is 0.3 and the probability of event B is 0.5, and events A and B are independent, the probability of both A and B occurring is ______.
A. 0.15
B. 0.8
C. 0.2
D. 0.6
答案：A。

因为事件A 和B 独立，所以两者同时发生的概率为两个事件概率的乘积，即0.3×0.5 = 0.15。

48. A bag contains 3 red balls and 2 blue balls. The probability of randomly drawing a red ball is ______.
A. 2/5
B. 3/5
C. 3/2
D. 2/3
答案：B。

袋子里一共有5 个球，其中3 个是红球，所以随机抽取一个红球的概率是3/5。

49. The probability of an impossible event is ______.
A. 0
B. 1
C. Between 0 and 1
D. Undefined
答案：A。

不可能事件发生的概率为0。

50. If the probability of winning a game is 0.4, the probability of losing the game is ______.
A. 0.4
B. 0.6
C. 0
D. 1
答案：B。

因为赢或输是两种互斥的情况，所以输的概率是1 - 0.4 = 0.6 。