# High school + combinatorial number - examples

1. Menu On the menu are 12 kinds of meal. How many ways can we choose four different meals into the daily menu?
2. Word What is the probability that a random word composed of chars T, H, A, M will be MATH?
3. Chocolates In the market have 4 kinds of chocolates. How many ways can we buy 19 chocolates?
4. Sales From statistics of sales goods, item A buy 51% of people and item B buys 59% of people. What is the probability that from 10 people buy 2 item A and 8 item B?
5. N-gon How many diagonals has convex 11-gon?
6. Pairs From the five girls and four boys teachers have to choose one pair of boy and girl. A) How many such pairs of (M + F)? B) How many pairs where only boys (M + M)? C) How many are all possible pairs?
7. 2nd class combinations From how many elements you can create 4560 combinations of the second class?
8. Party At party overyone clink with everyone. Together, they clink 171 times. How many people were at the party?
9. Lines In how many points will intersect 14 different lines, where no two are parallel?
10. Commitee A class consists of 6 males and 7 females. How many committees of 7 are possible if the committee must consist of 2 males and 5 females?
11. Family What is the probability that a family with 7 childrens have: exactly 5 girls? 7 girls and 0 boys? Consider the birth probability of a girl is 48.69% and boy 51.31%.
12. Bulbs The probability that the bulb can operate 5000 hours is 0.16. What is the probability that exactly one of three bulbs can operate 5000 hours?
13. Examination The class is 21 students. How many ways can choose two to examination?
14. Math logic There are 20 children in the group, each two children have a different name. Alena and John are among them. How many ways can we choose 8 children to be among the selected A) was John B) was John and Alena C) at least one was Alena, John D) maximum one w
15. Cinema How many ways can be divided 11 free tickets to the premiere of "Jáchyme throw it in the machine" between 6 pensioners?
16. Tournament Determine how many ways can be chosen two representatives from 34 students to school tournament.
17. The camp At the end of the camp a 8 friends exchanged addresses. Any friend gave remaining 7 friends his card. How many addresses they exchanged?
18. Circles How many different circles is determined by 9 points at the plane, if 6 of them lie in a straight line?
19. Three-digit numbers How many three-digit numbers are from the numbers 0 2 4 6 8 (with/without repetition)?
20. Combinatorics The city has 7 fountains. Works only 6. How many options are there that can squirt ?

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