Combinatorics - examples

Would you like to compute count of combinations?

  1. Rectangle
    diagonal In rectangle with sides 10 and 9 mark the diagonal. What is the probability that a randomly selected point within the rectangle is closer to the diagonal than to any side of the rectangle?
  2. 7 heroes
    7statocnych 5 heroes galloping on 5 horses behind. How many ways can sort them behind?
  3. No. of divisors
    triangle_div How many different divisors has number ??
  4. Flags
    vlajka_cz How many different flags can be made from colors white, yellow, red, blue, green, orange so that each flag consisted of three different colors?
  5. Ace
    ace From complete sets of playing cards (32 cards) we pulled out one card. What is the probability of pulling the ace?
  6. Vans
    shuttlevan In how many ways can 7 shuttle vans line up at the airport?
  7. Seating
    kupe_1 How many ways can 7 people sit on 3 numbered chairs (eg seat reservation on the train)?
  8. Pediatrician
    doctor Pediatrician this month of 21 working days takes 3 days holidays. What is the probability that on Monday will be at work?
  9. Bureau of Labor
    UPSVAR Bureau of Labor is a state institution that provides mike and the rest for their so-called clients. The mission of the Bureau of Labor is spend taxpayer money to provide relaxation and benefits to those who do not want to work. Popularly speaking sense the
  10. Guests
    hostia How many ways can 7 guests sit down on 9 seats standing in a row?
  11. 2nd class variations
    cards From how many elements you can create 6480 variations of the second class?
  12. Word
    words What is the probability that a random word composed of chars T, D, O, O, V, S, B, A, P, P, D, N, R, O, Ě will be PRAVDĚPODOBNOST?
  13. Shelf
    bookshelf.JPG How many ways are there to arrange 9 books on a shelf?
  14. Phone numbers
    old_phone How many 9-digit telephone numbers can be compiled from the digits 0,1,2,..,8,9 that no digit is repeated?
  15. Chocolates
    Chocolate In the market have 3 kinds of chocolates. How many ways can we buy 13 chocolates?
  16. Rectangles
    rectangles How many rectangles with area 2832 cm2 whose sides is natural numbers are?
  17. Two doctors
    dr_cvach Doctor A will determine the correct diagnosis with a probability 80% and doctor B with a probability 72%. Calculate probability of correct diagnosis if patient is diagnosed by both doctors.
  18. Dice
    dices How many times must throw the dice, the probability of throwing at least one three was greater than 90%?
  19. Football league
    football In the 2nd football league is 19 teams. How many ways can be filled first, second and third place?
  20. Playing cards
    playing_cards How many possible ways are to shuffle 7 playing cards?

Do you have interesting mathematical example that you can't solve it? Enter it and we can try to solve it.

To this e-mail address we will reply solution; solved examples are also published here. Please enter e-mail correctly and check whether you don't have a full mailbox.