# Combinatorial number - high school - math problems How many ways can we thread 4 red, 5 blue and 6 yellow beads on the thread?
2. 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.
3. Cube construction A 2×2×2 cube is to be constructed using 4 white and 4 black unit cube. How many different cubes can be constructed in this way? ( Two cubes are not different if one can be obtained by rotating the other. )
4. Two groups The group of 10 girls should be divided into two groups with at least 4 girls in each group. How many ways can this be done?
5. Classroom Of the 26 pupils in the classroom, 12 boys and 14 girls, four representatives are picked to the odds of being: a) all the girls b) three girls and one boy c) there will be at least two boys
6. Boys and girls There are 11 boys and 18 girls in the classroom. Three pupils will answer. What is the probability that two boys will be among them?
7. STRESSED word Each letter in STRESSED is printed on identical cards, one letter per card and assembled in random order. Calculate the probability that the cards spell DESSERTS when assembled.
8. Component fail There is a 90 percent chance that a particular type of component will perform adequately under high temperature conditions. If the device involved has four such components, determine the probability that the device is inoperable because exactly one of the.
9. Records Records indicate 90% error-free. If 8 records are randomly selected, what is the probability that at least 2 records have no errors?
10. Probability of malaria A survey carried out at a certain hospital indicates that the probability that a patient tested positive for malaria is 0.6. What is the probability that two patients selected at random (i) one is negative while the other tested positive? (i) both patien On the menu are 12 kinds of meal. How many ways can we choose four different meals into the daily menu?
12. Family 94 boys are born per 100 girls. Determine the probability that there are two boys in a randomly selected family with three children.
13. A student A student is to answer 8 out of 10 questions on the exam. a) find the number n of ways the student can choose 8 out of 10 questions b) find n if the student must answer the first three questions c) How many if he must answer at least 4 of the first 5 que
14. A pizza A pizza place offers 14 different toppings. How many different three topping pizzas can you order?
15. Three numbers We have three different non-zero digits. We will create all 3 digits numbers from them to use all 3 figures in each number. We add all the created numbers, and we get the sum of 1554. What were the numbers? There are 15 boys and 12 girls at the graduation party. Determine how many four couples can be selected.
17. Dice We throw 10 times a play dice, what is the probability that the six will fall exactly 4 times?
18. Families 2 There are 729 families having 6 children each. The probability of a girl is 1/3 and the probability of a boy is 2/3. Find the the number of families having 2 girls and 4 boys.
19. Diagonals What x-gon has 54 diagonals?
20. 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?

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