Suppose 9 cards are numbered with the 9 digits from 1 to 9

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In summary, for Part I of Q1, there are 504 possible hands where order matters, and for Part II, there are 9 possible hands where order doesn't matter. For Q2, there are 792 ways to choose 5 cards out of 12 face cards in a standard 52 card deck.
  • #1
r-soy
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I try to solve this queation and see >>

suppose 9 cards are numbered with the 9 digits from 1 to 9 . A 3 card hand is dealt , 11 card at time . How many hands are possible where :

I ) order is taken into considreation
II ) order is not taken into considreation

I ) 9P3 = 504
II) 9C1 = 9

----

Q2 : From a standerd 52 card deack how many 5 card hands will have all face cards ? ( consider only Jaks , queens and kings to be the face card ?

13C3.13C2
= 22.308
 
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I want help were are you ?
 
  • #3
For Q1, Part I, you are right.

For Part II, your answer is 9? But look, I can name ten different hands:

123
124
125
126
127
128
129
134
135
136

Hint: The only difference between part I and part II is that order doesn't matter.


For Q2, I'm not really sure what's going on. I see you're taking combinations out of 13, which is the number of ranks. But that's not right, because first of all, a deck has 52 cards in it and the cards are dealt without replacement. But you're not concerned with the 52 cards, only with the ranks that are face cards. There are 12 of those cards total. So the question is asking, "How many ways can you choose five cards out of 12 cards?"
 

1. What is the probability of drawing a card with an even number?

The probability of drawing a card with an even number is 4/9, since there are 4 even numbers (2, 4, 6, 8) out of a total of 9 cards.

2. If I draw a card and put it back in the deck, what is the probability of drawing the same number again?

The probability of drawing the same number again is 1/9, since there is only one card with each number and putting it back in the deck does not affect the chances of drawing that number again.

3. What is the expected value of the sum of two randomly drawn cards?

The expected value of the sum of two randomly drawn cards is 10, since the sum of all the numbers from 1 to 9 is 45 and there are 9 possible combinations of two cards, giving an average of 5 for each combination.

4. If I draw two cards and multiply the numbers on them, what is the probability of getting a perfect square?

The probability of getting a perfect square is 3/9 or 1/3, since there are three perfect squares (1, 4, 9) out of a total of 9 possible products.

5. What is the probability of drawing a card with a prime number?

The probability of drawing a card with a prime number is 4/9, since there are 4 prime numbers (2, 3, 5, 7) out of a total of 9 cards.

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