Combinatorics - problems

Would you like to compute count of combinations?

  1. 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?
  2. Morse alphabet
    morse_code Calculate how many words of Morse code to create compiling commas and dots in the words of one to five characters.
  3. Sales
    tesco From statistics of sales goods, item A buy 54% of people and item B buys 58% of people. What is the probability that from 3 people buy 2 item A and 1 item B?
  4. Dices
    dices_2 We will throw two dice. What is the probability that the ratio between numbers on first and second dice will be 1:2?
  5. Lock
    combination-lock Combination lock will open when the right choice of 5 numbers (from 1 to 12 inclusive) is selected. A. How many different lock combinations are possible? B. Is he combination lock named appropriately?
  6. Bulbs
    bulb The probability that the bulb can operate 4000 hours is 0.13. What is the probability that exactly one of eight bulbs can operate 4000 hours?
  7. Raffle
    tombola_tickets In the pool is numbers from 1 to 135. What is the probability that a randomly selected number is not a prime number?
  8. Bulbs
    bulbs In the box are 18 bulbs with power 60 W, 8 bulbs with power 40 W and 19 with 50 W. Calculate probability that a randomly selected bulb is:
  9. Football league
    football_3 In the football league is 16 teams. How many different sequence of results may occur at the end of the competition?
  10. Word
    words What is the probability that a random word composed of chars T, I, O, D, I will be IDIOT?
  11. Football league
    football In the 2nd football league is 19 teams. How many ways can be filled first, second and third place?
  12. Events
    items Event J has probability of 0.17. What is the probability that the event J occurs in:
  13. Kids
    kids How many different ways can sit 5 boys and 5 girls in line, if girls want to sit on the edge?
  14. Seating rules
    school_class In a class are 22 seats but in 2.B class are only 14 students. How many ways can student seat? (The class has 11 benches. A bench is for a pair of students.) Result (large number) logarithm and thus write down as powers of 10.
  15. The dice
    hracia-kocka What is the probability of events that if we throw a dice is rolled less than 6?
  16. Combinations
    circles.GIF How many different combinations of two-digit number divisible by 4 arises from the digits 3, 5 and 7?
  17. 7 heroes
    7statocnych 5 heroes galloping on 5 horses behind. How many ways can sort them behind?
  18. 2nd class variations
    cards From how many elements you can create 6480 variations of the second class?
  19. 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.
  20. Playing cards
    playing_cards How many possible ways are to shuffle 7 playing cards?

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