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aleksley [76]
3 years ago
12

What is the probability of these events when we randomly select a permutation of {1,2, ..., n} where n≥4? a) 1 precedes 2 c) 1 i

mmediately precedes 2 d) n precedes 1 and n−1 precedes 2
Mathematics
1 answer:
Paraphin [41]3 years ago
3 0

Answer:

a) 1/2

b) 1/n

c) 1/4

Step-by-step explanation:

a) For each permutation, either 1 precedes 2 or 2 precedes 1. For each permutation in which 1 precedes 2, we can swap 1 and 2 to obtain a permutation in which 2 preceds 1. Thus, half of the total permutations will involve in 1 preceding 2, hence, the probability for a permutation having 1 before 2 is 1/2.

c) If 2 is at the start of the permutation, then it is impossible for 1 to be before 2. If that is not the case, then 1 has a probability of 1/n-1 to be exactly in the position before 2. We can divide in 2 cases using the theorem of total probability,

P( 1 immediately preceds 2) = P (1 immediately precedes 2 | 2 is at position 1) * P(2 is at position 1) + P(1 immediately precedes 2 | 2 is not at position 1) * P(2 is not at position 1) = 0 * 1/n + (1/n-1)*(n-1/n) = 1/n.

d) We can divide the total of permutations in 4 different groups with equal cardinality:

  • Those in which n precedes 1 and n-1 precedes 2
  • those in which n precedes 1 and 2 precedes n-1
  • those in which 1 precedes n and n-1 precedes 2
  • those in which 1 precedes n and 2 precedes n-1

All this groups have equal cardinality because we can obtain any element from one group from another by making a permutations between 1 and n and/or 2 and n-1.

This means that the total amount of favourable cases (elements of the first group) are a quarter of the total, hence, the probability of the event is 1/4.

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Can somebody help answer all these right plz!<br> (WILL MARK BRAINLIEST)<br> Thanks!
attashe74 [19]

Answer:

22.8, 28, 3, 12.2, 31.5, 6

Step-by-step explanation:

15.

17-(4.4/2)+8

17-(2.2)+8

25-2.2

22.8

16.

(7^2-7)/3*2

(49-7)/3*2

42/3*2

14*2

28

17.

14/2-16/4

7-4

3

18.

3.2+3*6/2

3.2+18/2

3.2+9

12.2

19.

7*.3*(8.1+6.9)

2.1*(15)

31.5

20.

11-(7.6+7.4)/5

11-(15)/3

11-5

6

Hope it helped!

8 0
3 years ago
Read 2 more answers
How do I graph an inequality in one variable?
Masja [62]
It depends on the variable.

If it's something like x < 2, your graph would be a vertical line at x = 2, and everything to left of that line shaded in (because of the less than).

Similarly for y, except it would be a horizontal line with either everything above or below shaded.

You can have other equations like 0<x<4 where everything between x = 0 and x = 4 would be shaded
7 0
3 years ago
Given that f(x)= 2x+1 and g(x)= x^2 +2x+1 find (F+g)(2). Find (F.g)(x) find f(x)/g find f(2) +g(-2)?
Pepsi [2]

Answer:

(f+g)(2) = 14

f(g(x)) = 2x^2 + 4x +3

\frac{f(x)}{g(x)} = \frac{2x+1}{x^2+2x+1}

f(2) + g(-2) = 6

Step-by-step explanation:

Function composition and transformation combines functions together using operations such as addition, subtraction, multiplication, division and substitution. To find each, perform the operation with the functions f(x) = 2x+1 and g(x) = x^2 + 2x +1.

(f+g)(x) is the functions f and g added together with 2 substituted for x.

(f+g)(x) = 2x+1 + x^2 +2x + 1 = x^2 + 4x + 2\\(f+g)(2) = 2^2 + 4(2) + 2 = 14

(f·g)(x) is function composition that means f(g(x)) or substitute g(x) into f(x).

f(g(x)) = 2(x^2+2x+1)+1 = 2x^2 + 4x+2 + 1\\f(g(x)) = 2x^2 + 4x +3

f(x) / g(x) is division of the two functions. Division can only occur with polynomials if they share the same factors or things which multiply to create them. If none are present, do not simplify.

\frac{f(x)}{g(x)} = \frac{2x+1}{x^2+2x+1}

This cannot be simplified.

f(2) + g(-2) means find the function value of f at 2 and the function value of g at -2 then add them together.

f(2)+g(-2) = 2(2)+1 + ((-2)^2+2(-2) + 1)\\f(2) + g(-2) = 5 + (4-4+1)\\f(2) + g(-2) = 5 +1 = 6

7 0
3 years ago
Read 2 more answers
Calculate the arithmetic sequence in which a9=17 and the common difference is d=-2.1
jek_recluse [69]

Answer:

S_{31}=71.3


Step-by-step explanation:

The nth term of an arithmetic sequence is given by the formula,

U_n=a_1+(n-1)d


We were given that the 9th term is 17.


\Rightarrow 17=a_1+(9-1)(-2.1)


\Rightarrow 17=a_1+(8)\times(-2.1)


\Rightarrow 17=a_1-\frac{84}{5}


\Rightarrow 17+\frac{84}{5}=a_1


\Rightarrow a_1=\frac{169}{5}


The sum of the first n-terms is given by the formula,


S_n=\frac{n}{2}(2a_1+(n-1)d)


To find S_{31}, we substitute n=31, a_1=\frac{169}{5} and d=-2.1.


\Rightarrow S_{31}=\frac{31}{2}(2(\frac{169}{5}+(31-1)(-2.1))


\Rightarrow S_{31}=\frac{31}{2}(2(\frac{169}{5}+(30)(-2.1))



\Rightarrow S_{31}=\frac{31}{2}(\frac{23}{5})


\Rightarrow S_{31}=\frac{713}{10}


\Rightarrow S_{31}=71.3


The correct answer is D















8 0
3 years ago
Read 2 more answers
8 divde by 1/6 equals 48 because<br><br>​
nika2105 [10]

Proof:

8\div\frac{1}{6}=\frac{8}{1}\div \frac{1}{6}=\frac{8}{1}\times\frac{6}{1}=\frac{8\times6}{1}=\frac{48}{1}=48 \\

6 0
3 years ago
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