Find 50 probability math problems for the second year of junior high school, not too long

1. There is a cube, and the 6 faces are marked with 1 6 These 6 integers, and if you throw this cube once, the probability that the number on the upward side is even is ( ).

a． 1/3 b．1/6 c． 1/2 d． 1/4

2. Throw three uniform six-sided cubes marked with at the same time, and the numbers that appear are , then the probability of the length of the three sides of the right triangle is ( ).

a．1/216 b． 1/72 c．1/12 d． 1/36

The application of probability.

3. In order to prevent and control imported influenza A (H1N1), a city hospital set up a prevention and control team for patients with fever and runny nose, and decided to transfer 3 people from the 5 backbone physicians in the Department of Internal Medicine (including A), then the probability that A must be transferred to the prevention and control team is ( ).

a．3/5 b． 2/5 c． 4/5 d． 1/5

Answer] A4, the bag contains 1 red ball, 2 white balls, 3 black balls, they are exactly the same except for the color, from the bag to touch a ball arbitrarily, the probability of the ball is a white ball

Answer] 1 3

5. A and B play a poker game, and the rules of the game are: from the three playing cards with the number on the card. A random card is drawn, and after it is put back, another card is randomly drawn, and if the sum of the two cards drawn is an odd number, A wins; If the sum of the two drawn cards is even, then B wins, and the game (fill in "fair" or "unfair").

6. In an opaque cloth bag, there are 60 red, black and white glass balls, in addition to the color, the shape, size, texture, etc. are exactly the same Xiao Gang found that the frequency of touching red and black balls was stable at 15% and 45%, so the number of white balls in the pocket was likely to be one.

Answer] 247. In the two spaces of 3 2 (2), fill in any "+" or " " , then the probability of the result of the operation is 3 is

Answer] 1 2

8. There are 2 white balls and a yellow ball in an opaque cloth bag, which are the same except for the different colors

Answer] 89. Xiaofang tosses a coin 10 times, 7 times it is heads, and when she tosses the 11th time, the probability of heads is up

Answer] 1 2

10. One night, Xiaowei helped his mother clean the teacups, the three teacups only had different colors, one of them had no lid, and suddenly the power went out, Xiaowei had to match the cup lid and the teacup randomly, and the color was completely matched with the correct probability

Answer] 1 6

11. There are a number of red balls and white balls in a pocket, there is no difference between these two balls except for the color, the balls in the bag have been stirred, and a ball is taken out of the pocket blindfolded, and the probability of taking out the red ball is

1) What is the probability of removing the white ball?

2) If there are 18 white balls in the bag, how many red balls are in the bag?

Because: the average number of rings obtained by the first nine shots of the nickname is higher than the average number of rings obtained by the first four shots, and the first four times are set to a total of X-rings.

Therefore: (x+ > x 4

x+ >x/4

x <

Set the tenth ring to hit the Y ring.

x+>= 10*

y >=

y >=

y >=

So at least the ring.

1. The title means that the red balls account for 1 4 of the total, that is, there are 2 or 3 red balls, then the number of white balls is 7 or 8. ·

2. The probability is 1 4, which means that only one of the four types of arrangement can form a triangle. 3,5,7 can form a triangle, so x and 3,5,7 cannot form a triangle, so x>=12 or 0

4 60 360 + 2 90 360 + 100 15 360-10 2 3 + 1 2 + 100 Closed 24-10 = 16 3-10 14 3 yuan.

Human Supplement 2009-06-01 18:19

That is to say, if you spend 10 yuan to shake, you will lose 14 3 = yuan each time.

Since it is two dice, all the possibilities that can be rolled are 6*6 2=18;

Scheme 1: The sum of two numbers is equal to 8 There are three possibilities, accounting for one-sixth of all possible rolling;

The sum of two numbers equal to 9 has two possibilities, accounting for one in nine of all possible rolls. Obviously unfair, better for A!

Scheme 2: The sum of two numbers is greater than 8 There are 6 possibilities, accounting for one-third of all possible rolling; is the absolute value of the difference between the two numbers less than 2 (11; 22；33；44；55；66；12；23；34；45；56) The 11 possibilities, which account for 11 out of 18 out of all possible rolls, are clearly more favorable to B and are still unfair.

In short, as long as the proportion of the probability of throwing the total possibility is the same under the specified conditions, it is considered fair, and the simplest: the sum of the two numbers is greater than 8, and the absolute value of the difference between the two numbers is less than 1, and the probability of both parties rolling under this restriction accounts for one-third of all possibilities.

In an impermeable pocket there are 4 red balls and 2 white balls. They are exactly the same except for the color. If you touch a small ball from a random bag, the chance of touching a red ball is 4 (4+2)=2 3

There are 50 people, there are 50 probabilities, the probability of the same month is 12 50, and the probability of those two people having the same birthday is 12 50 1 30 2 50

In a large group, 50 people are randomly selected, the number of people with the same birthday is counted, and the average value of the two people is sampled several times, and the probability of two people having the same birthday can be roughly estimated.

Is it okay to ask a question?

This is 101, not 100.

Misread, it's 100

Question 1: The probability of waiting for a lottery to get super excellent is: 40%;

The probability of getting the best in the second draw is: 39%;

The probability of winning the super-excellent twice at the same time is: 40%x39%=, then the probability of not drawing the super-excellent at the same time is 1-156 1000=

The probability of waiting for the two best to be drawn at one time is: 35%;

The probability of getting the best in the second draw is: 34%;

The probability of winning the super-excellent twice at the same time is: 35%x34%=, then the probability of not drawing the super-excellent at the same time is the probability of waiting for the quasi-two excellent draws at the same time: 25%;

The probability of the second draw is 24%;

The probability of winning the quasi-two advantages at the same time is: 25%x24%=6%, and the probability of not drawing the quasi-two advantages at the same time is 1-6%=94%.

Correct the "two excellent" points:

The probability of waiting for the two best to be drawn at one time is: 35%;

The probability of winning the two excellent results in the second draw is: 34%;

The probability of drawing two excellent at the same time is: 35%x34%=, then the probability of not drawing two excellent at the same time is to ask questions, the teacher helps me draw a tree diagram, I just learned about probability, a little dizzy to answer sorry, classmate, there is no pen and paper around now, wait for a while and then draw a second question for you: choose super excellent 1000

It is possible to have everyone's birthday on any of the 365 days of the year. are equal to 1 365, then select n people, and the probability of their birthdays is different.

365*364*363...365-n+1) 365 to the nth power.

Therefore, the probability that at least two of n people have the same birthday is.

p=1-365*364*363...365-n+1) 365 to the nth power.

Here the value given n is 50, and the probability of substitution is p=

Using the method of random sampling, 50 people are randomly selected in a large group, the number of two people with the same birthday is counted, and the average value of the two people is sampled multiple times, and the probability of two people having the same birthday can be roughly estimated in 50 people.

This problem could not be devised and the result was 50 365, which is 10 73.

Be careful next time you ask a question!