Pre-Algebra [Combinations]

posted by .

Need help with these-

1.How many groups of 4 fabrics can be selected from 7 fabrics?

2.The school photographer wants to photograph 3 students from a club with 14 members. How many combinations can be made?

3.Philip wishes to check 2 books out of his school library. If the library contains 800 books, in how many ways might Philip make his choice of books?

Thanks
-MC

  • Pre-Algebra [Combinations] -

    C(n,k) = n!/[ (n-k)!k! ]
    for example if n = 7 and k = 4
    C(7,4) = 7! /[ 3! 4! ]
    = 7*6*5 *4! /[3*2*1 *4!]
    4! cancels top and bottom
    6 cancels top and bottom
    = 7*5
    =35

    Now try n = 14, k = 3
    and n = 800, k = 2

  • Pre-Algebra [Combinations] -

    Nevermind I got all the answers:
    1. 35 groups
    2. 364 combinations
    3. 319,600 choices

    -MC

  • Pre-Algebra [Combinations] -

    ..Oops just saw that Damon. Thanks!
    -MC

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Math: Permutations and Combinations

    Need a verification: Combinations of n items taken r at a time: C9n,r)= n!/(n-r)!*r! C(8,0) 8!/(8-0)!*(0)! = 8!/8!*0! = 0 or Answer is 0 or 1?
  2. Algebra/Trig

    The members of a men’s club have a choice of wearing black or red vests to their club meetings. A study done over a period of many years determined that the percentage of black vests worn is 60%. If there are 10 men at a club meeting …
  3. Fashion and fabrics

    For Which type of fabrics r ball point mchne ndles recomended n why.
  4. Math

    Teng is designing a house and in each room he can choose from tiles, floorboards, or carpet for the floor. a. How many combinations of flooring materials are possible if her designs a 2 room studio?
  5. Algebra

    A sales clerk at a local deli made the chart below for popular lunch combinations. What is the individual price for a salad?
  6. Maths

    At a boarding school, in the evening, 9 students always take walks in groups of 3. How can the groups be arranged so that each person walks in a group with every other person exactly once in 4 days?
  7. Urgent maths homework help

    At a boarding school, in the evening, 9 students always take walks in groups of 3. How can the groups be arranged so that each person walks in a group with every other person exactly once in 4 days?
  8. Combinations and Permutations

    A committee of 3 members is selected from a club made up of 10 junior members and 20 senior members. What is the expected number of juniors in the committee?
  9. EASY Pre-Algebra

    In the following situation, determine whether you are asked to determine the number of permutations or combinations. Then do the calculation. How many ways can the four offices of chairman, vice chairman, secretary, and treasurer be …
  10. Probability: Combinations

    The students in Mrs. Mandel’s class need to choose two class representatives from six nominated students. How many different combinations of class representatives are possible?

More Similar Questions