Combinatorics - problems

  1. Boys and girls
    boy_6 There are eight boys and nine girls in the class. There were six children on the trip from this class. What is the probability that left a) only boys b) just two boys
  2. Inverted nine
    In the hotel,, Inverted nine" each hotel room number is divisible by 6. How many rooms we can count with three-digit number registered by digits 1,8,7,4,9?
  3. PIN code
    pin_2 PIN on Michael credit card is a four-digit number. Michael told this to his friend: • It is a prime number - that is, a number greater than 1, which is only divisible by number one and by itself. • The first digit is larger than the second. • The second.
  4. Mumbai
    Mumbai A job placement agency in Mumbai had to send ten students to five companies two to each. Two of the companies are in Mumbai and others are outside. Two of the students prefer to work in Mumbai while three prefer to work outside. In how many ways assignment
  5. No. of divisors
    triangle_div How many different divisors has number ??
  6. 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?
  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 purple, yellow, red, white, blue, green, orange so that each flag consisted of three different colors?
  10. Vans
    shuttlevan In how many ways can 7 shuttle vans line up at the airport?
  11. Seating
    kupe_1 How many ways can 10 people sit on 0 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. 2nd class variations
    cards From how many elements you can create 6972 variations of the second class?
  16. Word
    words What is the probability that a random word composed of chars T, H, A, M will be MATH?
  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 23 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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