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german
2 years ago
11

21x =7? A. x=3 B. None of these C. x=147 D. x=28

Mathematics
1 answer:
Varvara68 [4.7K]2 years ago
6 0

Answer: B

Step-by-step explanation:

To isolate x, you divide both sides by 21

21x=7

\frac{21x}{21}=\frac{7}{21}

x = 7/21

Simplify by dividing both the numerator and denominator by 7

x = 1/3

Since, 1/3 is not an option, B is the correct answer

You might be interested in
28, 45, 12, 34, 36, 45, 19, 20
Alborosie

1) Mean of the set of data: 29.88

2) Mean absolute deviation: 10.13

3) See explanation

Step-by-step explanation:

1)

The mean of a set of data it is calculated as

\bar x = \frac{1}{N}\sum x_i

where

N is the number of data in the set

x_i is the value of each point in the  dataset

For the set of data in this problem, we have:

x_i =[28, 45, 12, 34, 36, 45, 19, 20]

And the number of values is

N = 8

Therefore, we can calculate the mean:

\bar x = \frac{1}{8}(28+ 45+ 12+ 34+ 36+ 45+ 19+ 20)=\frac{239}{8}=29.88

2)

The mean absolute deviation of a set of data is given by

\delta = \frac{1}{N}\sum |x_i-\bar x|

where

N is the number of values in the dataset

x_i are the single values

\bar x is the mean of the dataset

The dataset here is

x_i =[28, 45, 12, 34, 36, 45, 19, 20]

The mean, calculated in part 1), is

\bar x = 29.88

And

N = 8

Therefore the mean absolute deviation is

\delta = \frac{1}{8}(|28-29.88|+|45-29.88|+|12-29.88|+|34-29.88|+|36-29.88|+|45-29.88|+|19-29.88|+|20-29.88|)=\frac{81}{8}=10.13

3)

The mean of a dataset is the sum of the single values of the dataset divided by the number of values. The mean represents the value \bar x for which, if the dataset would have N values all equal to \bar x, the sum of the values of the dataset would be the same as the sum of the actual values.

The mean absolute deviation for a set of data represents the average of the absolute deviations of the single points from the mean of the dataset. This quantity gives a measure of the "dispersion" of the points around the mean: in fact, the larger the mean absolute deviation is, the more the points are "spread" around the mean of the dataset. Instead, if the mean absolute deviation is small, it means that the points are closer to the mean value.

Learn more about mean and spread of a distribution:

brainly.com/question/6073431

brainly.com/question/8799684

brainly.com/question/4625002

#LearnwithBrainly

7 0
4 years ago
Solve for X<br><br> A. 9<br> B. 10<br> C.36<br> D.60
Wewaii [24]

I believe it C u doing online school for virtual academy

6 0
3 years ago
Read 2 more answers
Jason and his children went into a movie theater where they sell drinks for $4 each and pretzels for $5 each. Jason has $65 to s
klemol [59]

Answer:

Number of drink = 5

Number of pretzel = 9

Step-by-step explanation:

Given:

Cost of each drink = $4

Cost of each pretzel = $5

Total money = 65

Total number of drink and pretzel = 14

Find:

Number of drink and pretzel

Computation:

Number of drink = x

Number of pretzel = 14 - x

So,

x(4) + (14-x)5 = 65

4x + 70 - 5x = 65

x = 5

Number of drink = 5

Number of pretzel = 14 - x

Number of pretzel = 14 - 5 = 9

4 0
3 years ago
Read 2 more answers
Find an input that yield an output of -1 rule y=-2x+33
djyliett [7]

Input (x-value)

Output (y-value)

You need to find the x-value that produces a y-value of -1. Since you know:

y = -1       Use the rule, and substitute/plug this into the equation

y = -2x + 33       Plug in -1 for "y" in the equation since y = -1

-1 = -2x + 33        Subtract 33 on both sides

-1 - 33 = -2x + 33 - 33

-34 = -2x      Divide -2 on both sides to get "x" by itself

\frac{-34}{-2}=\frac{-2x}{-2}

17 = x

An input of 17 yields an output of -1

3 0
3 years ago
PLEASE HELP SOON I DONT UNDERSTAND THIS QUIZ
Fantom [35]

1. h₀ = 70  

v₀ = 0 since the rock is dropped it has no initial velocity  

when the rock hits the ground the height = 0  

plug into the formula  

0 = -4.9t² + 0(t) + 70  

0 = -4.9t² + 70  

Add 4.9t² to both sides  

4.9t² = 70  

Divide both sides by 4.9  

t² = 14.2857142857  

Take the square root of both sides  

t = 3.7796447301  

t ≈ 3.8 seconds

I am not doing the rest I only did one just to help you understand a bit more

6 0
3 years ago
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