Combinatorics - examples - page 3
At party overyone clink with everyone. Together, they clink 171 times. How many people were at the party?
A school survey found that 12 out of 15 students like pizza. If 6 students are chosen at random, what is the probability that all 6 students like pizza?
- 2nd class combinations
From how many elements you can create 4560 combinations of the second class?
How many different ways can sit 8 boys and 3 girls in line, if girls want to sit on the edge?
In how many points will intersect 14 different lines, where no two are parallel?
A class consists of 6 males and 7 females. How many committees of 7 are possible if the committee must consist of 2 males and 5 females?
- Monty Hall
Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. W
The lottery is 60000 elk in which 6200 wins. What is the probability that the purchase of 12 elks won nothing?
- Hockey players
After we cycle five hockey players sit down. What is the probability that the two best scorers of this crew will sit next to each other?
- Area codes
How many 6 digit area codes are possible if the first number can't be zero?
- School trip
Class has 17 students. What different ways students can be accommodated in the hostel, where available 3× 2-bed, 1× 3-bed and 2× 4-bed rooms. (Each room has its own unique number)
How many different 7 digit natural numbers in which no digit is repeated, can be composed from digits 0,1,2,3,4,5,6?
3 children pulled 12 different toys from a box. Many ways can be divided toys so that each children had at least one toy?
What is the probability that a family with 7 childrens have: exactly 5 girls? 7 girls and 0 boys? Consider the birth probability of a girl is 48.69% and boy 51.31%.
- Three digits number
How many are three-digit integers such that in they no digit repeats?
In the box are 8 white, 4 blue and 2 red components. What is the probability that we pull one white, one blue and one red component without returning?
On each side of the square is marked 10 different points outside the vertices of the square. How many triangles can be constructed from this set of points, where each vertex of the triangle lie on the other side of the square?
The probability that the bulb can operate 5000 hours is 0.16. What is the probability that exactly one of three bulbs can operate 5000 hours?
- Cars plates
How many different licence plates can country have, given that they use 3 letters followed by 3 digits?
How many ways can select 4 fields on classic chess board with 64 fields, so that fields don't has the same color?
Would you like to compute count of combinations?