# Combinatorics + reason - math problems

#### Number of problems found: 158

• Training
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 Kov
• Tv dinner tray
I'm trying to calculate total possible unique potential combinations, but I'm trying to solve for a tv dinner tray with 4 little sections for one each of: meat, veggie, starch, dessert. What makes this more complex is we have different types of meats/vegg
• 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?
• Shooters
In army regiment are six shooters. The first shooter target hit with a probability of 49%, next with 75%, 41%, 20%, 34%, 63%. Calculate the probability of target hit when shooting all at once.
• Desks
A class has 20 students. The classroom consists of 20 desks, with 4 desks in each of 5 different rows. Amy, Bob, Chloe, and David are all friends, and would like to sit in the same row. How many possible seating arrangements are there such that Amy, Bob,
• 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.
• Cards
Suppose that are three cards in the hats. One is red on both sides, one of which is black on both sides, and a third one side red and the second black. We are pulled out of a hat randomly one card and we see that one side of it is red. What is the probabi
• Twins with friend
The twins Danka and Janka went to the cinema with their friend Betka. Only six seats in the second row were available in the cinema. The twins want to sit next to each other, and Danka always to the right of Janka and Betka near one of them. How many do t
• In the orchard
In the orchard, they planted 25 apple trees, 20 pears, 15 plums and 40 marbles. A strong late frost, however, destroyed a fifth of all new trees. Unfortunately, it was all the trees of one kind of fruit. What is the probability that the plums have died ou
• Pairs of socks
Ferdinand has twelve pairs of socks, and one sock is leaky. What is the probability of putting on a leaky sock?
• Cinema
How many ways can be divided 11 free tickets to the premiere of "Jáchyme throw it in the machine" between 6 pensioners?
• Hockey game
In the hockey game was made six goals. Czech played against Finland. Czechs won 4:2. In what order to fall goals? How many game sequences were possible during the game?
• Glass with icecream
We have 6 kinds of ice cream and 5 kinds of fruit. We put 3 cups of ice cream and 2 fruits into each glass. How many can unique decorated glasses be?
• Five letters
How many ways can five letters be arranged?
• Birth
Let's assume that the probability of the birth of a boy and a girl in the family is the same. What is the probability that in a family with five children, the youngest and oldest child is a boy?
• Competition
15 boys and 10 girls are in the class. On school competition of them is selected 6-member team composed of 4 boys and 2 girls. How many ways can we select students?
• A married
A married couple planned to have 3 children. i. List the possible combinations of the sexes of 3 children. Use B for boy and G for girl. ii. Calculate the probability that all three children would be of the same gender
• Table and chairs
Four people should sit at a table in front of a row of 7 chairs. What is the probability that there will be no empty chair between them if people choose their place completely at random?
• Throw
We throw 2 times with 2 dices. What is the probability that the first roll will fall more than sum of 9 and the second throw have sum 3 or does not have the sum 4?
• 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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