1, there are 13 students, at least two of whom have birthdays in the same month. This is a (random) event with a probability of (1-c (365, 13)/360 13).
2. The whole school has 6 classes in Grade One, 8 classes in Grade Two and 4 classes in Grade Three. Now we have to choose a class to participate in the city sports meeting, and the probability of winning the third grade is (4/ 18 =2/9).
3. When you toss a uniform coin, the probability is (1/2), when you toss two coins, the probability is (1/4), and when you toss three coins, the probability is (1/8).
The probability that a class will have physical education class tomorrow is 5/8, so the probability that this class will not have physical education class tomorrow is (3/8).
5. Nicknames have written three letters and three envelopes. If he randomly puts three letters into three envelopes, the probability that the stationery of one letter is the same as the envelope is (1/3).
6. The unqualified rate of product A is 9%, and the unqualified rate of product B is 8%. It is more reliable to buy product B. ..
7. The weather forecast shows that the probability of precipitation in Beijing is 60% and that in Nanjing is 80% tomorrow, so it is more likely that Nanjing residents will travel with umbrellas tomorrow.
8. There are eight identical balls. Design a ball-touching game so that the probability of hitting the white ball is 1/2, the probability of hitting the red ball is 1/4, and the probability of hitting the yellow ball is 1/4. Then there are (4) white balls, (2) red balls and (2) green balls.
Second, multiple choice questions
1, the probability of an event cannot be (d)
A. 100% b 30% c 50% d 200%
2, the probability of the following events is 0 event is (b)
A. When you flip a coin, you get a face facing up.
Within b 1 hour, walk100km.
C. When you roll the dice, you get 6 points.
D.it will be sunny tomorrow
3. In the lottery, if the probability of winning is 0.34, then the probability of not winning is (d).
A.0.34 B.0. 17 C.0.76 D.0.66
4. "1product is randomly selected from products that have never been inspected, and it is qualified" is (d).
A. Inevitable events B. Impossible events
C. Deterministic events D. Uncertain events
5. if a? =b？ , then a = b, this event belongs to (c)
A. Impossible events B. Inevitable events
C. Uncertain events D. None of the above is true
6. Xiaogang threw a uniform coin, and it was thrown face up nine times in a row. Can you tell me the probability (c) that he throws a coin face up for the first time 10?
A.0b.1C.1/2 d. Not sure.
7. Two shooters shoot a target independently of each other. The probability of A hitting the target is 0.9, and that of B hitting the target is 0.8. In a shot, the probability that A and B hit the target at the same time is (A).
A.0.72 b.0.85 c.0.1d. Not sure.
Third, answer questions.
1. A building has four gates. If someone enters through one door and exits through another, what are the different ways? 16
2. How many non-repetitive three-digit numbers can be formed by using the four numbers 1, 2, 3 and 4? What is the probability that it contains three digits of the number 2? 24, 1/4
4. A little brother tore all the labels of 10 boxes of vegetables. Now it looks like every box is the same, but he knows that there are three boxes of corn, two boxes of spinach, four boxes of beans and one box of potatoes. He took out a box at random and opened it.
1. What is the probability that there is corn in the box? 3/ 10
2. What is the probability that there are beans in the box? 2/5
3. What is the probability that it is not spinach in the box? 3/ 10
4. What is the probability that there are beans or potatoes in the box? 1/2
5. A deck of playing cards was stripped of King and King, and the nickname was 10. The rest were given to Xiaohong and Xiaogang to play games. The two agreed to draw 10 times each. (After drawing back), each card was drawn, with Xiaohong drawing a red card 1 point and Xiaogang drawing a black card 1 point.
1, Xiaohong randomly draws one. What are the chances that she will draw a cube? 1/4
What are the chances of her drawing a black card? 1/2
2. If the game is fair, how many cards of 10 held by Xiaoming should be red cards? five