# Combinatorics - math word problems

1. Red balls
In the bag there are 3 red, 12 blue and 8 green balls. How many red balls we must be attached to the bag if we want the probability of pulling out the red balls was 20%?
2. Word MATEMATIKA
How many words can be created from the word MATEMATIKA by changing the order of the letters, regardless of whether or not the words are meaningful?
3. Six on dice
What is the probability that when throwing two dice will fall at least one six?
4. Sum or product
What is the probability that two dice fall will have the sum 7 or product 12?
5. Sum on dice
We have two dice. What is the greater likelihood of fall a total sum 7 or 8 ? (write 7, 8 or 0 if the probabilities are the same)?
6. Three-digit
How many three-digit natural numbers do not have the number 7?
7. Lines
How many lines can be draw with 8 points, if three points lie on one line and the other any three points do not lie on the same line?
8. Digits
How many five-digit numbers can be written from numbers 0.3,4, 5, 7 that is divided by 10 and if digits can be repeated.
9. Doctor 2
A doctor noted the Diastolic Blood Pressure (DBP) of a large number of patients. Later, he scrambled the data to keep the privacy of his patients. Based on the scrambled dataset, he finds that the lower inner fence is equal to 50 and the upper inner fen
10. Pins 2
how many different possible 4 digits pins can be found on the 10-digit keypad?
11. Three reds
What is the probability that when choosing 3 carats from seven carats, all 3 reds will be red?
12. Tricolors
From the colors - red, blue, green, black and white, create all possible tricolors.
13. VCP equation
Solve the following equation with variations, combinations and permutations: 4 V(2,x)-3 C(2,x+ 1) - x P(2) = 0
14. Roses 2
Aunt Rose went to the flower shop to buy a bouquet with three roses. The flower shop had white, yellow and red roses. How many different flowers bouquet can a flower make for Aunt Rose create? Write all the bouquet options.
15. Page numbering
The book has 88 pages. How many times is the number 4 used for the book numbering?
16. Digits
How many natural numbers greater than 4000 which are formed from the numbers 0,1,3,7,9 with the figures not repeated, B) How many will the number of natural numbers less than 4000 and the numbers can be repeated?
17. 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
18. Alarm clock
The old watchmaker has a unique digital alarm in its collection that rings whenever the sum of digits of the alarm is equal to 21. Find out when the alarm clock will ring. What is their number? List all options . ..
19. First class
The shipment contains 40 items. 36 are first grade, 4 are defective. How many ways can select 5 items, so that it is no more than one defective?
20. Cards
From a set of 32 cards we randomly pull out three cards. What is the probability that it will be seven king and ace?

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