Stacking rings on fingers by decreasing stack size (permutations)

In summary, the number of ways to arrange rings on fingers can be represented by the equation x=5P5(5P5+5P4+5P3). This is derived by considering all possible configurations of rings on fingers, and using the formula for permutations to determine the number of ways for each configuration. This equation takes into account all cases, including when there are multiple rings on a single finger or multiple stacks of rings.
  • #1
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Homework Statement
Let ##x## be the numbers of ways that a woman can wear ##5## distinct rings on ##5## fingers of her right hand, given that she can stack maximum of ##3## rings on any finger.
Relevant Equations
N/A
When she is stacking ##5## rings, then there are ##5P5## configurations when it comes to arranging rings, and each configuration can be arranged on her fingers in ##5P1## ways (choose one finger from 5 to put that configuration on).

When she is stacking ##4## rings, then we have two objects; a configuration of ##4## rings, and a ring outside. The number of configurations is also given by ##5P5##. For the fingers, however, we now choose two fingers out of five to put the objects on, or, ##5P2##.

The same reasoning goes for the last case, so$$x=5P5(5P3+5P2+5P1)$$


EDIT: I understood the problem statement in a peculiar way. I don't know how that happened. However, the logic is kind of still the same, and I think$$x=5P5(5P5+5P4+5P3)$$
 
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  • #2
I didn't consider the cases where we can stack 2 rings on 2 fingers, for example, etc ..

To make it easier on myself, I can first ignore how many rings are making a specific stack, and just consider objects to be arranged on the five fingers. For example, I'll just look at a configuration of ##2, 2, 1## as just ##3## objects to be arranged.

The number of objects I can possible have is ##5, 4, 3## and ##2##, so ##x=5P5a+5P4b+5P3c+5P2d##, where those variables need to be determined.

When we have ##5## objects, this means that I have a ring per finger, so ##a=1##.

When we have ##4## objects, this means that there is a stack of ##2## and ##3## single rings. The number of ways I can gather a stack of ##2## is ##5P2##, so ##b=5P2##.

When we have ##3## objects, then we either have a stack of ##3## rings, and ##2## single rings, or ##2## stacks of ##2## rings, and single ring.
For the case where we have a stack of ##3##, then this is similar to the above case, i.e we have ##5P3## ways of arranging that stack.
Basically, I can represent one configuration of the set of objects to be permuted by ##\{(r_ar_b),(r_cr_d),r_e\}##. At first, I have ##5P2## ways of choosing ##(r_ar_b)##, then I'd be left with ##3## rings, so I can choose ##(r_cr_d)## in ##3P2## ways. Moreover, I'll be doing twice the same permutation eventually since I'd have to permute ##\{(r_ar_b),(r_cr_d),r_e\}## and ##\{(r_cr_d),(r_ar_b),r_e\}##.
Finally, I get ##c=5P3+\frac{5P2\times3P2}{2}##.

When we have ##2## objects, then we either have ##4,1##, or ##3, 2##.
The first case is again like the others, so ##5P4## permutations.
For ##3, 2##, it is like the last case. We have ##\{(r_ar_br_c), (r_dr_e)\}##, so ##5P3\times2P2##.
Thus ##d=5P4+5P3\times2P2##.
 
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1. What is the purpose of stacking rings on fingers by decreasing stack size?

The purpose of stacking rings on fingers by decreasing stack size is to create a visually appealing and symmetrical look. It is a popular trend in jewelry fashion and can also serve as a way to showcase multiple rings at once.

2. How many different permutations are possible when stacking rings on fingers by decreasing stack size?

The number of permutations depends on the number of rings being stacked. For example, if there are 4 rings, there are 24 different permutations possible. This can be calculated using the formula n! (n factorial), where n is the number of rings.

3. Is there a specific order in which the rings should be stacked?

There is no specific order in which the rings should be stacked. However, it is common to start with the largest ring and work your way down to the smallest ring for a more balanced look.

4. Can any type of ring be used for stacking?

Yes, any type of ring can be used for stacking as long as they fit comfortably on the fingers and do not cause any discomfort or restriction of movement.

5. Are there any risks or precautions to consider when stacking rings on fingers?

There are a few potential risks to consider when stacking rings on fingers. If the rings are too tight, they can restrict blood flow and cause discomfort. It is also important to be cautious when wearing rings with sharp edges or stones that can scratch or damage nearby rings. Additionally, be mindful of any allergies to certain metals or materials in the rings.

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