Reason + multiplication principle - math problems
Number of problems found: 68
- Number 4
Kamila wrote all natural numbers from 1 to 400 inclusive. How many times did she write the number 4?
- Two-element combinations
Write all two-element combinations from elements a, b, c, d.
- Big numbers
How many natural numbers less than 10 to the sixth can be written in numbers: a) 9.8.7 b) 9.8.0
How many matches will be played in a football tournament in which there are two groups of 5 teams if one match is played in groups with each other and the group winners play a match for the overall winner of the tournament?
- Research in school
For particular research in high school, four pupils are to be selected from a class with 30 pupils. Calculate the number of all possible results of the select and further calculate the number of all possible results, if it depends on the order in which th
- Three-digit numbers
We have digits 0,1,4,7 that cannot be repeated. How many three-digit numbers can we write from them? You can help by listing all the numbers.
- Birthday paradox
How large must the group of people be so that the probability that two people have a birthday on the same day of the year is greater than 90%?
- Gold, silver, bronze
How many ways can we divide gold, silver, bronze medails if there are 6 people competing?
- Five letters
How many ways can five letters be arranged?
- The test
The test contains four questions, and there are five different answers to each of them, of which only one is correct, the others are incorrect. What is the probability that a student who does not know the answer to any question will guess the right answer
- Fall sum or same
Find the probability that if you roll two dice, it will fall the sum of 10, or the same number will fall on both dice.
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?
How many different ways can three people divide 7 pears and 5 apples?
How many three-digit natural numbers are divisible by 25?
- Boys and girls
There are 20 boys and 10 girls in the class. How many different dance pairs can we make of them?
- 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?
- Graduation party
There are 15 boys and 12 girls at the graduation party. Determine how many four couples can be selected.
- One three
We throw two dice. What is the probability that max one three falls?
- Holidays with grandmam
We have packed three T-shirts - white, red, orange and five pants - blue, green, black, pink and yellow. How many days can we spend with the old mother if we put on a different combination of clothes every day?
- Bookshelf and books
How many ways can we place 7 books in a bookshelf?