Reason + multiplication principle - math problems

Number of problems found: 68

  • Number 4
    numbers_3 Kamila wrote all natural numbers from 1 to 400 inclusive. How many times did she write the number 4?
  • Two-element combinations
    combinatorics Write all two-element combinations from elements a, b, c, d.
  • Big numbers
    numbers_1 How many natural numbers less than 10 to the sixth can be written in numbers: a) 9.8.7 b) 9.8.0
  • Tournament
    futball_ball 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
    numbers_1 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
    numbers_2 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
    holland 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
    olympics How many ways can we divide gold, silver, bronze medails if there are 6 people competing?
  • Five letters
    charH How many ways can five letters be arranged?
  • The test
    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
    dices2 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.
  • Birth
    probability 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?
  • Divide
    hrusky How many different ways can three people divide 7 pears and 5 apples?
  • Twenty-five
    prime How many three-digit natural numbers are divisible by 25?
  • Boys and girls
    dancers There are 20 boys and 10 girls in the class. How many different dance pairs can we make of them?
  • Two groups
    skola 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
    dancers There are 15 boys and 12 girls at the graduation party. Determine how many four couples can be selected.
  • One three
    dice We throw two dice. What is the probability that max one three falls?
  • Holidays with grandmam
    saty 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
    bookshelf How many ways can we place 7 books in a bookshelf?

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