Answer:
9.11*10^-4 %
Step-by-step explanation:
To find the probability, you simply need to find the possible outcomes that allows no rooks to be in danger, and the possible amount of ways to place the rooks.
For the first outcome, you start by putting 1 rook in the first columns, you have 8 possible rows to do this. The next rook in the next column will only have 7 possible rows, as you have to exclude the one where the previous rook is located. The next rook, 6 possibilities, the next 5, and so on. So we conclude that the total amount of ways so that none of the rooks can capture any of the other rooks is 8*7*6*5*4*3*2*1 = 8! = 40320
In order to find the total amount of ways to place the rooks, you can just use a combinatoric:
![\left[\begin{array}{ccc}64\\8\end{array}\right]= \frac{64!}{8!(64-8)!} = 4.43*10^9](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D64%5C%5C8%5Cend%7Barray%7D%5Cright%5D%3D%20%5Cfrac%7B64%21%7D%7B8%21%2864-8%29%21%7D%20%3D%204.43%2A10%5E9)
Then:
P = 
Percent decrease = (original number - new number) / original number....* 100
= (45 - 27.5) / 45.....* 100
= 17.5 / 45....* 100
= 0.3888 * 100
= 38.9 % decrease <== thats rounded
Answer:
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Answer:
520 miles
Step-by-step explanation:
A rectangle is a two-dimensional shape with two sets of equal, parallel sides. These dimensions are the length (L) and the width (W). The formula for the rectangle's area is the product of the two dimensions. The formula for perimeter is
P = 2L + 2W
Since
A = LW = 64
W = 64/L
Substituting to the formula for perimeter would be,
P = 2L + 2(64/L)
P = 2L + 128/L