Combination Question: 8 Things Divided in Groups of 5 & 3

In summary, there are two ways to divide 8 different things into groups of 5 and 3 - either choosing 5 items out of 8 for one group and 3 items for the other, or arranging 8 items in a row and labeling them to go into two groups.
  • #1
lionely
576
2

Homework Statement




In how many ways can 8 different things be divided into groups of 5 and 3.


Homework Equations





The Attempt at a Solution



I thought it be just be 8C5 X 8C3

but also might it be 8C5 x 3C3 since if you take 5 you only have 3 left to select from?
 
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  • #2
lionely said:

Homework Statement




In how many ways can 8 different things be divided into groups of 5 and 3.


Homework Equations





The Attempt at a Solution



I thought it be just be 8C5 X 8C3

but also might it be 8C5 x 3C3 since if you take 5 you only have 3 left to select from?

If you pick the three for one group you automatically leave 5 for the other group.
 
  • #3
Another way to look at this is to arrange the 8 items in a row, then label those to go into the first group "0" and those to go into the second group "1". How many different way are there to order 5 "0"s and 3 "1"s?
 
  • #4
Thank you
 

1. What is the total number of groups that can be formed from 8 things divided in groups of 5 and 3?

The total number of groups that can be formed is 56. This is calculated by finding the number of ways to choose 5 items from 8 and then multiplying it by the number of ways to choose 3 items from the remaining 3.

2. How many things will be in each group?

There will be 5 things in each group of 5 and 3 things in each group of 3. This is because the question states that the 8 things are divided into groups of 5 and 3.

3. Can the groups have overlapping items?

No, the groups cannot have overlapping items. This is because the question specifies that the 8 things are divided into groups, which implies that each item can only belong to one group.

4. How many items will be left over after forming all the groups?

After forming all the groups, there will be 2 items left over. This is because 8 cannot be divided equally into groups of 5 and 3.

5. Can this question be solved using a combination formula?

Yes, this question can be solved using a combination formula. The formula for finding the number of ways to choose k items from a group of n items is nCk = n! / (k!(n-k)!). In this case, n = 8 and k = 5 or 3.

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