Combinatorial number - math word problems There are 15 boys and 12 girls at the graduation party. Determine how many four couples can be selected.
2. Records Records indicate 90% error-free. If 8 records are randomly selected, what is the probability that at least 2 records have no errors?
3. Genetic disease One genetic disease was tested positive in both parents of one family. It has been known that any child in this family has a 25% risk of inheriting the disease. A family has 3 children. What is the probability of this family having one child who inherited.
4. Word What is the probability that a random word composed of chars E, Y, G, E, R, O, M, T will be the GEOMETRY?
5. Chocolates In the market have 3 kinds of chocolates. How many ways can we buy 14 chocolates?
6. Rectangles How many rectangles with area 3032 cm2 whose sides is natural numbers are?
7. Candy How many ways can divide 10 identical candies to 5 children?
8. 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?
9. Stacks Annie has a total of \$ 702. The money must be divided into stacks so that each buyer has the same amounth of dollars. How many options she have?
10. N-gon How many diagonals has convex 11-gon?
11. 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?
12. 2nd class combinations From how many elements you can create 4560 combinations of the second class?
13. Party At the party everyone clink with everyone. Together, they clink 406 times. How many people were at the party?
14. Lines In how many points will intersect 14 different lines, where no two are parallel?
15. 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?
16. 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%.
17. 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?
18. Examination The class is 21 students. How many ways can choose two to examination?
19. 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
20. Cinema How many ways can be divided 11 free tickets to the premiere of "Jáchyme throw it in the machine" between 6 pensioners?

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