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const2013 [10]
3 years ago
8

1. All of the following are true except B. A. A random variable represents a numerical value assigned to an outcome of a probabi

lity experiment. In most applications, discrete random variables represent counted data. C. In most applications, continuous random variables represent measured data. D. The expected value of a discrete random variable is equal to the standard deviation of the random variable.
Mathematics
1 answer:
kolezko [41]3 years ago
6 0

Answer:

The true statements are :

A. A random variable is a numerical description of the outcome of a statistical experiment.

B. In most​ applications, discrete random variables represent counted​ data.

C. In most applications, continuous random variables represent measured data.

Step-by-step explanation:

It is true statement that,

A. A random variable is a numerical description of the outcome of a statistical experiment.

B. In most​ applications, discrete random variables represent counted​ data.

C. In most applications, continuous random variables represent measured data.

The false statement is -

D. The expected value of a discrete random variable is equal to the standard deviation of the random variable.

Reason -

The mean value, or expected value, of a discrete random variable X is given by the following equation:

μ = E(x) = ∑ x p(x)

And

The variance of a discrete random variable is given by the following formula:

σ²=∑ (x−μ)² P(x)

And

The square root of the variance, or, in other words, the square root of σ², is the standard deviation of a discrete random variable :

σ = √σ²

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Prove or disprove (from i=0 to n) sum([2i]^4) <= (4n)^4. If true use induction, else give the smallest value of n that it doe
ddd [48]

Answer:

The statement is true for every n between 0 and 77 and it is false for n\geq 78

Step-by-step explanation:

First, observe that, for n=0 and n=1 the statement is true:

For n=0: \sum^{n}_{i=0} (2i)^4=0 \leq 0=(4n)^4

For n=1: \sum^{n}_{i=0} (2i)^4=16 \leq 256=(4n)^4

From this point we will assume that n\geq 2

As we can see, \sum^{n}_{i=0} (2i)^4=\sum^{n}_{i=0} 16i^4=16\sum^{n}_{i=0} i^4 and (4n)^4=256n^4. Then,

\sum^{n}_{i=0} (2i)^4 \leq(4n)^4 \iff \sum^{n}_{i=0} i^4 \leq 16n^4

Now, we will use the formula for the sum of the first 4th powers:

\sum^{n}_{i=0} i^4=\frac{n^5}{5} +\frac{n^4}{2} +\frac{n^3}{3}-\frac{n}{30}=\frac{6n^5+15n^4+10n^3-n}{30}

Therefore:

\sum^{n}_{i=0} i^4 \leq 16n^4 \iff \frac{6n^5+15n^4+10n^3-n}{30} \leq 16n^4 \\\\ \iff 6n^5+10n^3-n \leq 465n^4 \iff 465n^4-6n^5-10n^3+n\geq 0

and, because n \geq 0,

465n^4-6n^5-10n^3+n\geq 0 \iff n(465n^3-6n^4-10n^2+1)\geq 0 \\\iff 465n^3-6n^4-10n^2+1\geq 0 \iff 465n^3-6n^4-10n^2\geq -1\\\iff n^2(465n-6n^2-10)\geq -1

Observe that, because n \geq 2 and is an integer,

n^2(465n-6n^2-10)\geq -1 \iff 465n-6n^2-10 \geq 0 \iff n(465-6n) \geq 10\\\iff 465-6n \geq 0 \iff n \leq \frac{465}{6}=\frac{155}{2}=77.5

In concusion, the statement is true if and only if n is a non negative integer such that n\leq 77

So, 78 is the smallest value of n that does not satisfy the inequality.

Note: If you compute  (4n)^4- \sum^{n}_{i=0} (2i)^4 for 77 and 78 you will obtain:

(4n)^4- \sum^{n}_{i=0} (2i)^4=53810064

(4n)^4- \sum^{n}_{i=0} (2i)^4=-61754992

7 0
3 years ago
What equation is equivalent to x + 8 = 21
san4es73 [151]

Answer:

x= 13

Step-by-step explanation:

x + 8 = 21

x + 8-8 = 21-8

x = 13

7 0
3 years ago
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Use Heron's Formula to find the area of triangle ABC. Round your answer to the nearest whole number.
Scrat [10]

Step-by-step explanation:

use herons formula

√s(s-a)(s-b)(s-c)

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S=20

and a,b,c are sides of triangle

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=√20.3.11.6

=62.92

nearest whole number is 63

option B is correct

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If 1/2 gallon of paint covers 1/12 of a wall then how much paint is needed for the entire wall
netineya [11]

1/2 gallon of paint covers 1/12 of a wall , 12 times as much paint will cover 12 times the area you can solve this by 12*1/2=6.

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3 years ago
Evaluate 6x + 3y - 4, if x = 20 and y = 2.<br> ОА. 16<br> Ов. 20<br> Ос. 36<br> D 8
lord [1]

6x + 3y - 4

6(20)+3(2)-4

Do the brackets first.

120+6-4

120+2

122

Answer is 122

4 0
2 years ago
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