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3 years ago

Please, i need help with letter B

Mathematics

2 answers:

Valentin [98]3 years ago

7 0

I think it might be 58

Arte-miy333 [17]3 years ago

5 0

Answer:

Step-by-step explanation:

6*8+2*2+3*2=58

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Multiply and combine like terms:<br> -5x – 4(9 – 2x)

Alex777 [14]

-5x-36+8x

3x-36

3(x-18)

3 0

2 years ago

Calculate the sample mean and sample variance for the following frequency distribution of heart rates for a sample of American a

spin [16.1K]

Answer:

$Mean = 68.9$

$s^2 =18.1$ --- Variance

Step-by-step explanation:

Given

$\begin{array}{cccccc}{Class} & {51-58} & {59-66} & {67-74} & {75-82} & {83-90} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

Solving (a): Calculate the mean.

The given data is a grouped data. So, first we calculate the class midpoint (x)

For 51 - 58.

$x = \frac{1}{2}(51+58) = \frac{1}{2}(109) = 54.5$

For 59 - 66

$x = \frac{1}{2}(59+66) = \frac{1}{2}(125) = 62.5$

For 67 - 74

$x = \frac{1}{2}(67+74) = \frac{1}{2}(141) = 70.5$

For 75 - 82

$x = \frac{1}{2}(75+82) = \frac{1}{2}(157) = 78.5$

For 83 - 90

$x = \frac{1}{2}(83+90) = \frac{1}{2}(173) = 86.5$

So, the table becomes:

$\begin{array}{cccccc}{x} & {54.5} & {62.5} & {70.5} & {78.5} & {86.5} \ \\ {Frequency} & {6} & {3} & {11} & {13} & {4} \ \end{array}$

The mean is then calculated as:

$Mean = \frac{\sum fx}{\sum f}$

$Mean = \frac{54.5*4+62.5*3+70.5*11+78.5*13+86.5*4}{6+3+11+13+4}$

$Mean = \frac{2547.5}{37}$

$Mean = 68.9$ -- approximated

Solving (b): The sample variance:

This is calculated as:

$s^2 =\frac{\sum (x - \overline x)^2}{\sum f - 1}$

So, we have:

$s^2 =\frac{(54.5-68.9)^2+(62.5-68.9)^2+(70.5-68.9)^2+(78.5-68.9)^2+(86.5-68.9)^2}{37 - 1}$

$s^2 =\frac{652.8}{36}$

$s^2 =18.1$ -- approximated

5 0

3 years ago

5 to the 2nd power

lana [24]

Answer:

Step-by-step explanation:

5 is the base

2 is the exponent

6 0

3 years ago

1/4 (20x−28) <2(x−3)+2

xeze [42]

Answer:

Step-by-step explanation:

1/4 x 20x - 1/4 x 28<2x - 6 + 2

5x - 28/4<2x - 4

5x - 2x<-4 + 28/4

3x<-4/1 + 28/4

3x<-16 + 28/4

3x<12/4

3x<3

3x/3<3/3

x<1

6 0

3 years ago

Marvin wants to purchase a rectangular rug. It has an area represented by the expression 4x^2+64x+256. what is the length and wi

jasenka [17]

Answer: the length and width are

(x + 8) and (x + 8)

Step-by-step explanation:

The rug has an area represented by the expression

Area = 4x² + 64x + 256.

The factors in the factored expressions represent the length and width of the rug.

Dividing the the equation by 4, it becomes

x² + 16x + 64 = 0

We would find two numbers such that their sum or difference is 16x and their product is 64x^2.

The two numbers are 8x and 8x. Therefore,

x² + 8x + 8x + 64 = 0

x(x + 8) + 8(x + 8) = 0

The factors are

(x + 8)(x + 8)

7 0

3 years ago