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Re: A fortune-teller uses 22 Major Arcana Tarot cards to perform [#permalink]
Please confirm the answer

I think E is right one.. here order will matter so we need to use P instead of C and reverse means we need to just double the card..
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Re: A fortune-teller uses 22 Major Arcana Tarot cards to perform [#permalink]
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devilmirror wrote:
A fortune-teller uses 22 Major Arcana Tarot cards to perform fortune telling. She will pick 3 cards to look at querent's past, present, and futuer. A card will have different meaning if it is reversed. How many possible ways can the fortune-teller read the fortune?

A) 1,540
B) 9,240
C) 12,320
D) 73,920
E) 79,464

Bonus: Same question. If she picks 10 cards, how many ways can she read the fortune?


The answer is D.

First card; 22 cards available and 2 possible interpretations = 22 x 2
Second card; 21 cards available and 2 possible interpretations = 21 x 2
Third card; 20 cards available and 2 possible interpretations = 20 x 2

Therefore, n(events) = (22x2)(21x2)(20x2) = 73,920

OR
n(events) = (\(2^3\))(P(22,3) = (8)(22x21x20) = 73,920

The answer is D.
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Re: A fortune-teller uses 22 Major Arcana Tarot cards to perform [#permalink]
devilmirror wrote:
devilmirror wrote:
A fortune-teller uses 22 Major Arcana Tarot cards to perform fortune telling. She will pick 3 cards to look at querent's past, present, and futuer. A card will have different meaning if it is reversed. How many possible ways can the fortune-teller read the fortune?

A) 1,540
B) 9,240
C) 12,320
D) 73,920
E) 79,464

Bonus: Same question. If she picks 10 cards, how many ways can she read the fortune?


The answer is D.

First card; 22 cards available and 2 possible interpretations = 22 x 2
Second card; 21 cards available and 2 possible interpretations = 21 x 2
Third card; 20 cards available and 2 possible interpretations = 20 x 2

Therefore, n(events) = (22x2)(21x2)(20x2) = 73,920

OR
n(events) = (\(2^3\))(P(22,3) = (8)(22x21x20) = 73,920

The answer is D.


I am puzzled. If three cards are used to tell past, present and future, will the order of these cards not matter?
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Re: A fortune-teller uses 22 Major Arcana Tarot cards to perform [#permalink]
devilmirror wrote:

Bonus: Same question. If she picks 10 cards, how many ways can she read the fortune?


n(events) = (2^10)(P(22,10))
= (1024)( 22! / (22-10)! ) = (1024)(22! / 12!) = (1024)(22x21x20x...x13)

= 2,402,866,180,915,200
= 2.4 thousand trillions
= 2.4 quadrillion ways

:shock: :shock: :shock:

I guess fortune tellers will never run out of their stories.
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Re: A fortune-teller uses 22 Major Arcana Tarot cards to perform [#permalink]
scthakur wrote:
I am puzzled. If three cards are used to tell past, present and future, will the order of these cards not matter?


Because the order of card is matter. That's why we use permutation.

Permutation: P(22,3) = 22 x 21 x 20 = 9,240

Note:
Combination: C(22,3) = 22 x 21 x 20 / 3! = 22 x 7 x 10 = 1,540
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Re: A fortune-teller uses 22 Major Arcana Tarot cards to perform [#permalink]
devilmirror wrote:
scthakur wrote:
I am puzzled. If three cards are used to tell past, present and future, will the order of these cards not matter?


Because the order of card is matter. That's why we use permutation.

Permutation: P(22,3) = 22 x 21 x 20 = 9,240

Note:
Combination: C(22,3) = 22 x 21 x 20 / 3! = 22 x 7 x 10 = 1,540



Then, where am I going wrong in my interpretation?
There are 22 cards and each card has two faces. Hence, there are a total of 44 cards to choose from. If I have to choose 3 out of 44 cards then the possible ways could be 44P3.
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Re: A fortune-teller uses 22 Major Arcana Tarot cards to perform [#permalink]
scthakur wrote:
devilmirror wrote:
scthakur wrote:
I am puzzled. If three cards are used to tell past, present and future, will the order of these cards not matter?


Because the order of card is matter. That's why we use permutation.

Permutation: P(22,3) = 22 x 21 x 20 = 9,240

Note:
Combination: C(22,3) = 22 x 21 x 20 / 3! = 22 x 7 x 10 = 1,540



Then, where am I going wrong in my interpretation?
There are 22 cards and each card has two faces. Hence, there are a total of 44 cards to choose from. If I have to choose 3 out of 44 cards then the possible ways could be 44P3.


If you Assume number of cards is 22x2 = 44 , due to 2 faces than permutations of chossing a card out of a pack of 44 is different. Now you have only 22 cards to choose and each have 2 faces. Hope it clear your doubt !
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Re: A fortune-teller uses 22 Major Arcana Tarot cards to perform [#permalink]
AmitGUPTA wrote:
If you Assume number of cards is 22x2 = 44 , due to 2 faces than permutations of chossing a card out of a pack of 44 is different. Now you have only 22 cards to choose and each have 2 faces. Hope it clear your doubt !



Thanks Amit. I know what mistake I made.
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Re: A fortune-teller uses 22 Major Arcana Tarot cards to perform [#permalink]
Good work devilmirror ....

Just reminded me of concepts of permutation that is order is important in permutation.. and in this case order is important.



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