1. I

    combinations question

    A committee of 5 is being formed from 15 adults and 18 children. In how many different ways could it be formed if at least 1 adult and 1 child must be included? I know how to do this with cases, and I know how to do this indirectly by finding all possibilities subtract the ones with no adults...
  2. J

    Unique combinations of set

    Let’s say i have set with the elements { 1,2,3,4,5,6,7,8,9,10,11,12,13,14}. Is there a formula how I can calculate how many unique combinations (the order of the elements are not relevant) there are possible. And this combination can be of every length (can have a length of 1, but also...
  3. 7

    [Help] The number of possible k-sided polygons in an m by n grid of dots

    Hello. :spin: This is my first post, so sorry for the potential mistakes below. A grid of dots has the dimensions m by n, where m is greater than or equal to n. Pick k dots from this grid in such a way that they form a polygon with k sides. In other words, no three dots can be collinear...
  4. G

    An infinite set of finite sequences of combinations of a finite set of elements

    An infinite set of finite sequences of combinations of a finite set of elements is an infinite uncountable set?
  5. G

    The number of all combinations of limited number of elements is infinite?

    The number of all possible consecutive combinations (sequences with beginning and end, finite sequences) of a limited number of elements with a limited number of changes from one combination to another (in one sequence) is infinite?
  6. C

    Find a recursive formula for the number of combinations

    I have some question integrating between combinatorics and recursive formulas. Generally, I have some difficulty with the concept of recursion, as well as with the recursion in programming unfortunately. I have some question to solve, and maybe you can guide me: Find a recursive...
  7. S

    How many combinations?

    Hiya I'm new here and in here to ask for help in my calculation. Like the title says i want to know how many possible combinations there are in a system but it isn't as easy as 20*19*18 etc. Basically there are ten sets of input panels and each panel has two switches, but only one can be...
  8. B

    Linear Combinations

    Write the following statement in formal mathematical notation, including the sigma notation: a. Any linear combination of a finite number of linear combinations of a given set of vectors {x1,x2,...,xn}, generates a linear combination of the given set of vectors. b. Prove the statement in part a.
  9. M

    Permutations and Combinations Problem

    There are n number of chocolates. We can pick either 1 or 3 chocolates at once. In how many ways can we pick all the chocolates? The n variable can have any value as 30,100,50 etc.
  10. D

    How many different 5-digit number combinations can be created?

    How many different 5-digit number combinations can be created using 5, 7ths and 3, 2s? 77777 | 5 222 | 3 So my first thought was to use this formula: n_{1} * n_{2} * ... * n_{n} So that I get: 5! = 5 * 4 * 3 * 2 * 1 but this is probably just calculating how many ways I can put all...
  11. R

    Total Combinations

    Hi Forum, I have 10 football matches being played on the weekend (Team 1 vs Team 2, Team 3 vs Team 4...Team 19 vs Team 20). I want to have a bet on a multi/parlay/accumulator with 4 teams in the bet. I want to work out how many combinations of 4 teams (each playing in different matches)...
  12. A

    Properties of non-integer combinations

    A linear combination, ax+by+...=z, where a,b,...,z∈Z and x,y,...∈Z. It is bound to yield an integer by the closure property of integers under the addition operation. This fact is used in computing g.c.d. among others. I want to know about properties of non-integer combination, i.e. given...
  13. A

    Does this problem fall into Combinations and Permutations easy question?

    Sorry I have this topic into the wrong forum almost close to probability and statistics maybe. I added a screen shot of the problem what would the process steps and answer be?
  14. O


    A group of 24 people, 16 of which are men, is forming a 5 person committee. How many different ways can the committee be formed if at least 1 of the members must be men? I thought the answer was, "(16 nCr 1) * (22 nCr 4), but it's not. What is the right equation?
  15. A

    Combinations with Variable r

    Boy there are lots of different questions about combinations on this site, but none seem to match mine. How do I figure number of combinations of n items - no repeats - but there is no limit on r, and order doesn't matter? In other words, think of a pizza menu. If there are two...
  16. E

    How Many Combinations Are There When 190 Balls Are Drawn Into Groups Of 10?

    Balls numbered from 1 to 190 are drawn without replacement into 19 groups of 10. The order within a group doesn't matter. Is the amount of combinations 190 C 10 * 180 C 10 * ... 10 C 10 ?
  17. W

    How many combinations of 4 weights on a line?

    I'm not a mathematician - but here is a question that I would appreciate some help with: I have 4 types of weights that need to be hung on an unlimited amount of lines. The weights are: 8 kg 7 kg 4 kg 3 kg There can be either 0, 1, 2, 3, 4, 5, or 6 weights hung on each line. The same weight...
  18. I

    Combinations in Algebra

    A bank requires its customers to use a 4-digit pin number for their ATM passwords. Distinguish how many different passwords that customers can choose from. Show and explain all of your work. Could anyone tell me how you would set up this problem?
  19. P

    How many Combinations - Real Business Question

    Hey all, I own a business and have an issue: I'm trying to work out the number of different product variations (for simplistic sake let's say we have a Toy Bear, Giraffe, and Elephant) that someone could purchase, for shipping purposes. If I have 3 different products, and the customer can...