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Alexeev081 [22]
3 years ago
14

A researcher posts a radio advertisement offering $35 in exchange for participation in a short study. The researcher accepts the

first eight people who respond to the advertisement. Which of the following statements is true about the sample? (5 points) a It is a valid sample because the first eight people were selected to participate. b It is not a valid sample because it is not a random sample of the population. c It is a valid sample because money was offered to participants. d It is not a valid sample because it is only a short study.
Mathematics
1 answer:
Mariulka [41]3 years ago
7 0
B) not valid because it is not a random sample

a) is biased because the first 8 people are unlikely to be representative of the population
c) is biased as offering money will influence the people who reply
d) is untrue because short studies are valid if they are representative
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Translate to an algebraic expression:<br><br> 12 less than the square of a number
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Answer:

12-x²

Step-by-step explanation:

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2 years ago
Which of the following is NOT equivalent to the nxn matrix A being invertible? A. The homogeneous system associated to A has a u
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Answer:

Option C

Step-by-step explanation:

  • For the matrix A of order n\times n to be invertible, its determinant must not be equal to zero, |A| \neq0, A^{- 1}  exists if- AC = CA = I, where I is identity matrix.
  1. The homogeneous equation with coefficient matrix A has a unique solution:

       AB = 0, B = A^{- 1}.0 = 0

      Thus, B = (0, 0, 0......., 0) is a unique solution

     2. The non - homogeneous equation system with coefficient matrix A has  a unique solution:

For an equation- AY = D

Y = A^{- 1}.D is a unique solution

     3. Every non homogeneous equation with coefficient matrix A is not consistent as:

For an equation- AY = D, has a solution.l Thus coefficient matrix is inconsistent whereas augmented matrix is.

      4. Rank of matrix A = n, Thus the column space of A is R^{n}

      5. Since, column space of A = R^{n}, thus x→xA is one-to-one

       

5 0
3 years ago
A child's sandbox is 5 feet wide, 4 feet long, and 3 feet deep. Grace fills the sandbox so that the sand is 2 ½ feet deep. What
8_murik_8 [283]

Answer:

the volume of sand is 50 ft^{3}

Step-by-step explanation:

This problem bothers on the mensuration of solid shapes, rectangular prism.

Given data

Length  l= 4 ft Width w= 5ft\\Height h = 3ft

if the sandbox is filled with sand of 2\frac{1}{2 } ft deep the volume of the sand in the box will be calculated based on the the depth of the sand

converting the depth of sand from mixed fraction to proper fraction we have 2\frac{1}{2} = \frac{5}{2}

the expression for the volume of a rectangular prism is

volume of sand = length * width* height

substituting our data into the expression we have

volume of sand= 5*4 * \frac{5}{2} \\volume of sand = \frac{100}{2} \\volume of sand = 50 ft^{3}

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A store pays $10.56 fora map of Africa and marks the price up by
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Essentially, 50% of $10.56 is $5.28.

This means that all we have to do is add $10.56 to $5.28, making <u>$15.84</u>


Side note: Another way that you can do this is by simply doing 1.5(10.56).

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