# Combinatorics - math word problems

1. Blocks There are 9 interactive basic building blocks of an organization. How many two-blocks combinations are there?
2. Find the 2 Find the term independent of x in the expansion of (4x3+1/2x)8
3. Pages counting There are pages numbered from 2 to 104 in the book. How many digits have to be printed to number the pages?
4. 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
5. Election 4 In a certain election there are 3 candidates for president 5 for secretory and 2 for tresurer. Find how many ways the election may (turn out/held).
6. 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
7. Normal distribution GPA The average GPA is 2.78 with a standard deviation of 4.5. What are students in the bottom the 20% having what GPA?
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. Probability of intersection Three students have a probability of 0.7,0.5 and 0.4 to graduated from university respectively. What is the probability that at least one of them will be graduated?
10. Balls From the bag with numbered balls (numbers 1,2,3,. ..20) we pick one ball. What is the probability of choosing a number containing 1?
11. Dice and coin A number cube is rolled and a coin is tossed. The number cube and the coin are fair. What is the probability that the number rolled is greater than 2 and the coin toss is head?
12. 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? There are 15 boys and 12 girls at the graduation party. Determine how many four couples can be selected.
14. 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.
15. Records Records indicate 90% error-free. If 8 records are randomly selected, what is the probability that at least 2 records have no errors?
16. 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

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