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3 years ago

Solve by the substitution method 2x + 9y=41 - 4x + y=13

Mathematics

1 answer:

melisa1 [442]3 years ago

6 0

Answer:

x=-2, y=5. (-2, 5).

Step-by-step explanation:

2x+9y=41

-4x+y=13

---------------

2(2x+9y)=2(41)

-4x+y=13

-----------------------

4x+18y=82

-4x+y=13

------------------

19y=95

y=95/19

y=5

2x+9(5)=41

2x+45=41

2x=41-45

2x=-4

x=-4/2=-2

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A cognitive psychologist wants to know whether memory performance is changed by old age. She randomly selects 7 elderly individu

defon

Answer:

$z = \frac{418.7-465.6}{\frac{53.6}{\sqrt{7}}}= -2.340$

Now we can calculate the p value with the following probability

$p_v =2*P(z$

If we use the commonly significance level of 0.05 we see that the p value is lower than these values we can conclude that the true mean is different from the value of 465.6 at 5% of significance

Step-by-step explanation:

Data provided

$\bar X=418.7$ represent the mean score on the standardized memory test

$\sigma=53.6$ represent the population standard deviation

$n=7$ sample size

$\mu_o =465.6$ represent the value that we want to verify

z would represent the statistic

$p_v$ represent the p value

System of hypothesis

We are interested to check if the memory performance for elderly individuals differs from that of the general population (mean different from 465.6), the system of hypothesis are then:

Null hypothesis: $\mu = 465.6$

Alternative hypothesis: $\mu \neq 465.6$

Since we know the population deviation we can use the z statistic from the z test for the true mean:

$z =\frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$ (1)

Replacing the info given we got:

$z = \frac{418.7-465.6}{\frac{53.6}{\sqrt{7}}}= -2.340$

Now we can calculate the p value with the following probability

$p_v =2*P(z$

If we use the commonly significance level of 0.05 we see that the p value is lower than these values we can conclude that the true mean is different from the value of 465.6 at 5% of significance

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4 years ago

What are the constants in this expression? x minus 3 + two-thirds minus StartFraction y over 2 EndFraction 1 and Negative 3 Nega

Sauron [17]

Answer:b

Step-by-step explanation:xxxxxxxxxxx

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4 years ago

Read 2 more answers

(From Unit 4, Lesson 1.)

damaskus [11]

The values of the missing sides is DE = 12 and AC = 6.5

<h3>Similar triangles</h3>

Two triangles are said to be similar if the ratio of their corresponding sides are in the same proportion. Also all the corresponding angles are congruent.

Using Pythagoras:

AC² = AB² + BC²

AC² = 2.5² + 6²

AC = 6.5

Using similar triangles:

BC / DE = AB / EF

6/DE = 2.5/5

DE = 12

The values of the missing sides is DE = 12 and AC = 6.5

Find out more on Similar triangles at: brainly.com/question/14285697

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2 years ago

If y varies directly as x and given y =9 when x= 5, fInd:

True [87]

Step-by-step explanation:

The statement

y varies directly as x is written as

<h3> $y \: \: \alpha \: \: x$ </h3>

So we have

First of all we must find the relationship between them

when

x = 5 and y = 9

We have

9 = 5k

Divide both sides by 5

$k = \frac{9}{5}$

So the equation for the variation is

$y = \frac{9}{5} x$

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$y = \frac{9}{5} \times 15 \\ = 9 \times 3$

We have the answer as

when y = 6

$6 = \frac{9}{5} x \\ 30 = 9x \\ x = \frac{30}{9}$

We have the answer as

$x = \frac{10}{3}$

Hope this helps you

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3 years ago

Which of the following patterns or images could best be described by a translation?

babunello [35]

Translations are all about shifting the same thing.
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3 years ago