# Reason + variations - math problems

1. 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?
2. Seating How many ways can 5 people sit on 4 numbered chairs (e. G. , seat reservation on the train)?
3. Toys 3 children pulled 12 different toys from a box. Many ways can be divided toys so that each children had at least one toy?
4. Three digits number How many are three-digit integers such that in they no digit repeats?
5. Seven-segmet Lenka is amused that he punched a calculator (seven-segment display) numbers and used only digits 2 to 9. Some numbers have the property that their image in the axial or central symmetry was again give some number. Determine the maximum number of three-d
6. 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?
7. 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?
8. Variations 3rd class From how many elements we can create 13,800 variations 3rd class without repeating?
9. Eight blocks Dana had the task to save the eight blocks of these rules: 1. Between two red cubes must be a different color. 2. Between two blue must be two different colors. 3. Between two green must be three different colors. 4. Between two yellow blocks must be four
10. Three-digit numbers How many three-digit numbers are from the numbers 0 2 4 6 8 (with/without repetition)?
11. Trainings The table contains tennis training schedule for Saturday's younger students during the winter indoor season. Before the start of the summer season is preparing a new training schedule. Tomas Kucera will be able to practice only in the morning, sisters Kova
12. Three digits number From the numbers 1, 2, 3, 4, 5 create three-digit numbers that digits not repeat and number is divisible by 2. How many numbers are there?
13. Chess How many different ways can initiate a game of chess (first pass)?
14. Dices throws What is the probability that the two throws of the dice: a) Six falls even once b) Six will fall at least once
15. Salami How many ways can we choose 5 pcs of salami if we have 6 types of salami for 10 pieces and one type for 4 pieces?
16. Pupils Four pupils is going via dark hall. Start at one side and have to get to the other side for 17 minutes. They have only one lamp for the trip. The corridor is narrow, they can therefore go up two pupils at a time and go at the slower speed. Each pupil went.
17. 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)?
18. Four swords Obelix has three helmets, four swords and five shields. How many swords must make at the blacksmith forge Metallurgix to be able to walk another 90 days in unique armor?
19. 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?
20. 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 . ..

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