Combinatorics - problems

  1. Election 4
    vote_1 In a certain election there are 3 candidates for president 5 for secretory and 2 for tresurer. Find how many ways the election may (turn out/held).
  2. Perfect cubes
    cubes3_7 Suppose a number is chosen at random from the set (0,1,2,3,. .. ,202). What is the probability that the number is a perfect cube?
  3. A student
    test_14 A student is to answer 8 out of 10 questions on the exam. a) find the number n of ways the student can choose 8 out of 10 questions b) find n if the student must answer the first three questions c) How many if he must answer at least 4 of the first 5 que
  4. Families 2
    family_24 There are 729 families having 6 children each. The probability of a girl is 1/3 and the probability of a boy is 2/3. Find the the number of families having 2 girls and 4 boys.
  5. Rectangle
    diagonal In rectangle with sides 3 and 10 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?
  6. No. of divisors
    triangle_div How many different divisors has number ??
  7. 7 heroes
    7statocnych 9 heroes galloping on 9 horses behind. How many ways can sort them behind?
  8. Ace
    ace From complete sets of playing cards (32 cards) we pulled out one card. What is the probability of pulling the ace?
  9. Flags
    vlajka_cz How many different flags can be made from colors white, red, green, purple, orange, yellow, blue so that each flag consisted of three different colors?
  10. Vans
    shuttlevan In how many ways can 6 shuttle vans line up at the airport?
  11. Seating
    kupe_1 How many ways can 7 people sit on 3 numbered chairs (eg seat reservation on the train)?
  12. Pediatrician
    doctor Pediatrician this month of 21 working days takes 3 days holidays. What is the probability that on Monday will be at work?
  13. Guests
    hostia How many ways can 5 guests sit down on 6 seats standing in a row?
  14. 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
  15. Word
    words What is the probability that a random word composed of chars T, H, A, M will be MATH?
  16. 2nd class variations
    cards From how many elements you can create 6972 variations of the second class?
  17. Shelf
    bookshelf.JPG How many ways are there to arrange 6 books on a shelf?
  18. Chocolates
    Chocolate In the market have 4 kinds of chocolates. How many ways can we buy 19 chocolates?
  19. 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?
  20. Two doctors
    dr_cvach Doctor A will determine the correct diagnosis with a probability 86% and doctor B with a probability 87%. Calculate probability of correct diagnosis if patient is diagnosed by both doctors.

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