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3 years ago

Can some one help me with this question its hard :( down below ill give brainliest

Mathematics

1 answer:

Jet001 [13]3 years ago

6 0

Answer: A. Suzy made an error going from Step 1 to Step 2.

Step-by-step explanation: Following the order of operations (PEMDAS), we know that exponents are dealt with before multiplication. Suzy used the distributive property of multiplication going from step 1 to step 2, rather than working with the exponent.

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A sofa is on sale for $219, which is 27% less than the regular price.<br> What is the regular price?

Tems11 [23]

Answer:

$300 was the regular price of the sofa.

Step-by-step explanation:

If $219 is 27% less than the regular price, then it represents 73% of the regular price.

Regular price = r.

r/1 x 73/100 = $219. Reverse this to find that $219/1 divided by 73/100 = r.

To divide fractions, reverse the second fraction and MULTIPLY:

$219/1 x 100/73 = 21900/73 = 300.

7 0

3 years ago

The least-squares regression model y =−3.4+5.2x and correlation coefficient r=−0.66 were calculated for a set of bivariate data

Makovka662 [10]

Answer:

$r=\frac{n(\sum xy)-(\sum x)(\sum y)}{\sqrt{[n\sum x^2 -(\sum x)^2][n\sum y^2 -(\sum y)^2]}}$

For this case the value of r = -0.66

Now we can calculate the determination coeffcient:

$r^2 = (-0.66)^2 = 0.4356$

And then we can conclude that 43.56% of the variation in y can be explained by the explanatory variable

And then 100-43.56 = 56.44 % of the variation in y that cannot be explained by the explanatory variable

Step-by-step explanation:

For this case we need to calculate the slope with the following formula:

$m=\frac{S_{xy}}{S_{xx}}$

Where:

$S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}$

$S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}$

$\bar x= \frac{\sum x_i}{n}$

$\bar y= \frac{\sum y_i}{n}$

And we can find the intercept using this:

$b=\bar y -m \bar x$

And the model obtained for this case is:

$y = -3.4 +5.2 x$

The correlation coefficient is a "statistical measure that calculates the strength of the relationship between the relative movements of two variables". It's denoted by r and its always between -1 and 1.

And in order to calculate the correlation coefficient we can use this formula:

$r=\frac{n(\sum xy)-(\sum x)(\sum y)}{\sqrt{[n\sum x^2 -(\sum x)^2][n\sum y^2 -(\sum y)^2]}}$

For this case the value of r = -0.66

Now we can calculate the determination coeffcient:

$r^2 = (-0.66)^2 = 0.4356$

And then we can conclude that 43.56% of the variation in y can be explained by the explanatory variable

And then 100-43.56 = 56.44 % of the variation in y that cannot be explained by the explanatory variable

8 0

2 years ago

A certain radioactive isotope has leaked into a small stream. Three hundred days after the leak, 3% of the original amount of t

sesenic [268]

If the half-life is t, then every t days, the amount of the radioactive isotope will be cut in half.
(1/2)^(number of half-lives) = 3%
number of half-lives = ln(0.03) / ln(0.5)
This gives the number of half-lives as 5.06.
Then 300 days = (5.06)(length of 1 half-life)
length of 1 half-life = 300 / 5.06 = 59.29 days

6 0

3 years ago

What chacharacteristic help you tell the difference between a rhombus and a rectangle? Explain.

jeka57 [31]

Rhombus -> 2 equivalent obtuse angles, 2 equivalent acute angles

vs.

Rectangle -> 4 equivalent right angles.

3 0

2 years ago

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What are the roots of the equation? x^2−x−42=0 Enter your answers in the boxes. x = and x =

Natasha_Volkova [10]

Your roots are x=7 and x=-6

8 0

3 years ago

Read 2 more answers