# Combinatorics - problems

Would you like to compute count of combinations?- Phone numbers

How many 9-digit telephone numbers can be compiled from the digits 0,1,2,..,8,9 that no digit is repeated? - Morse alphabet

Calculate how many words of Morse code to create compiling commas and dots in the words of one to five characters. - Sales

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? - Dices

We will throw two dice. What is the probability that the ratio between numbers on first and second dice will be 1:2? - 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? - Bulbs

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? - Raffle

In the pool is numbers from 1 to 135. What is the probability that a randomly selected number is not a prime number? - 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: - Football league

In the football league is 16 teams. How many different sequence of results may occur at the end of the competition? - Word

What is the probability that a random word composed of chars T, I, O, D, I will be IDIOT? - Football league

In the 2nd football league is 19 teams. How many ways can be filled first, second and third place? - Events

Event J has probability of 0.17. What is the probability that the event J occurs in: - Kids

How many different ways can sit 5 boys and 5 girls in line, if girls want to sit on the edge? - Seating rules

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. - The dice

What is the probability of events that if we throw a dice is rolled less than 6? - Combinations

How many different combinations of two-digit number divisible by 4 arises from the digits 3, 5 and 7? - 7 heroes

5 heroes galloping on 5 horses behind. How many ways can sort them behind? - 2nd class variations

From how many elements you can create 6480 variations of the second class? - Two doctors

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. - Playing cards

How many possible ways are to shuffle 7 playing cards?

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