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Y_Kistochka [10]
2 years ago
5

Eights rooks are placed randomly on a chess board. What is the probability that none of the rooks can capture any of the other r

ooks? Translation for those who are not familiar with chess: pick 8 unit squares at random from an 8x8 square grid. What is the probability that no two chosen squares share a row or a column?
Mathematics
1 answer:
erastova [34]2 years ago
7 0

Answer:

The probability is \frac{56!}{64!}

Step-by-step explanation:

We can divide the amount of favourable cases by the total amount of cases.

The total amount of cases is the total amount of ways to put 8 rooks on a chessboard. Since a chessboard has 64 squares, this number is the combinatorial number of 64 with 8, 64 \choose 8 .

For a favourable case, you need one rook on each column, and for each column the correspondent rook should be in a diferent row than the rest of the rooks. A favourable case can be represented by a bijective function  f : A \rightarrow A , with A = {1,2,3,4,5,6,7,8}. f(i) = j represents that the rook located in the column i is located in the row j.

Thus, the total of favourable cases is equal to the total amount of bijective functions between a set of 8 elements. This amount is 8!, because we have 8 possibilities for the first column, 7 for the second one, 6 on the third one, and so on.

We can conclude that the probability for 8 rooks not being able to capture themselves is

\frac{8!}{64 \choose 8} = \frac{8!}{\frac{64!}{8!56!}} = \frac{56!}{64!}

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valentina_108 [34]

Answer: I got 1, 4, and 7

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Step-by-step explanation:

4 0
2 years ago
CAN ANYONE HELP ME PLEASE? Jen Butler has been pricing​ Speed-Pass train fares for a group trip to New York. Three adults and fo
arsen [322]

Answer:

The adult ticket costs $18 and the children ticket costs $13.

Step-by-step explanation:

Let the price of the adult ticket be a.

Let the price of the children ticket be c.

Three adults and four children must pay $106. This implies that:

3a + 4c = 106 _______(1)

Two adults and three children must pay $75. This implies that:

2a + 3c = 75 ________(2)

We have two simultaneous equations:

3a + 4c = 106 _____(1)

2a + 3c = 75 ______(2)

Multiply (1) by 2 and (2) by 3 and subtract (1) from (2):

  6a + 9c = 225

- <u>(6a + 8c = 212)</u>

             c = $13

Put this value of c in (2):

2a + 3*13 = 75

2a + 39 = 75

=> 2a = 75 - 39

2a = 36

a = 36/2 = $18

Therefore, the adult ticket costs $18 and the children ticket costs $13.

4 0
3 years ago
There are 32 male performers in a dance recital. The ratio of men to women is 4:5. How many women are in the recital
Yanka [14]

Answer:

40

Step-by-step explanation:

if the ratio from men to woman is 4:5 and men are 32 that means w need to find a way to get to 32 using 4 and 8 x 4 is 32. so if we use 8 to get to 32 we need to use 8 on 5 aswell for it to be an equal ratio.

5 0
2 years ago
Simplify the expression (x^3- 5x^2 + 7x - 12) ÷ (x – 4) using long division​
Kisachek [45]

Answer:

{x}^{2} - x + 3

Step-by-step explanation:

Instead, since the divisor is in the form of x - c, use what is called Synthetic Division. Remember, in this formula, -cgives you the OPPOSITE terms of what they really are, so do not forget it. Anyway, here is how it is done:

4| 1 −5 7 −12

↓ 4 −4 12

_______________

1 −1 3 0 → {x}^{2} - x + 3

You start by placing the c in the top left corner, then list all the coefficients of your dividend [x³ - 5x² + 7x - 12]. You bring down the original term closest to c then begin your multiplication. Now depending on what symbol your result is tells you whether the next step is to subtract or add, then you continue this process starting with multiplication all the way up until you reach the end. Now, when the last term is 0, that means you have no remainder. Finally, your quotient is one degree less than your dividend, so that 1 in your quotient can be an {x}^{2}, the −1 [x] follows right behind it, and bringing up the rear, comes the 3, giving you the quotient of {x}^{2} - x + 3.

I am joyous to assist you anytime.

5 0
3 years ago
Someone help me with this ASAP
Archy [21]

Answer:

1:6

3/5×2=6/10

2:14

21÷3=7

2×7=14

8 0
2 years ago
Read 2 more answers
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