# Combinatorial number - examples - page 4

1. Points in plane
The plane is given 12 points, 5 of which is located on a straight line. How many different lines could by draw from this points?
2. Combinations
How many elements can form six times more combinations fourth class than combination of the second class?
3. Dice
We throw five times the dice. What is the probability that six fits exactly twice?
4. Dice
We throw 10 times a play dice, what is the probability that the six will fall exactly 4 times?
5. Boys and girls
There are eight boys and nine girls in the class. There were six children on the trip from this class. What is the probability that left a) only boys b) just two boys
6. Triangles
Five sticks with a length of 2,3,4,5,6 cm. How many ways can you choose three sticks to form three sides of a triangle?
7. Test
The teacher prepared a test with ten questions. The student has the option to choose one correct answer from the four (A, B, C, D). The student did not get a written exam at all. What is the probability that: a) He answers half correctly. b) He answers.
8. Raffle
There are 200 draws in the raffle, but only 20 of them win. What is the probability of at least 4 winnings for a group of people who have bought 5 tickets together?
9. Three students
Three students independently try to solve the problem. The first student will solve a similar problem with a probability of 0.6, the second student will solve at a probability of 0.55, and the third will solve at a probability 0.04. The problem is resolved
10. Diagonals
What x-gon has 54 diagonals?
11. A book
A book contains 524 pages. If it is known that a person will select any one page between the pages numbered 125 and 384, find the probability of choosing the page numbered 252 or 253.
12. Combinations 6
6 purses 9 flaps 12 straps Every combination must include 1 purse, 1 flap and 1 strap. How many possible combinations?
13. Subsets
How many 19 element's subsets can be made from the 26 element set?
14. Sweater
Dana confuses sweater and wool has a choice of seven colors. In how many ways she can choose from three colors to the sleeves?
15. Peaches
There are 20 peaches in the pocket. 3 peaches are rotten. What is the probability that one of the randomly picked two peaches will be just one rotten?
16. Bridge cards
How many bridge hands are possible containing 4 spades,6 diamonds, 1 club, and 2 hearts?
17. Cancel fractions
Compress the expression of factorial: (n+6)!/(n+4)!-n!/(n-2)!
18. Blocks
There are 9 interactive basic building blocks of an organization. How many two-blocks combinations are there?
19. Find the 2
Find the term independent of x in the expansion of (4x3+1/2x)8
20. Mumbai
A job placement agency in Mumbai had to send ten students to five companies two to each. Two of the companies are in Mumbai and others are outside. Two of the students prefer to work in Mumbai while three prefer to work outside. In how many ways assignment

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