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3 years ago

2/3(6y+9) Need help

Mathematics

2 answers:

Brut [27]3 years ago

7 0

Answer:

2(2y+3) or simpified completely 4y+6

Step-by-step explanation:

enot [183]3 years ago

4 0

Usually we have to get an answer for a bracket first, but in this case we can't because the terms inside the bracket are unlike.
But we can do multiplication using the distributive law.
Multiply the number in front of the bracket by each of the terms inside the bracket.
2
×
6
2
y
3
+
2
×
9
3
3
=
4
y
+
6

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Examination of a large sample of people revealed a relationship between calcium intake and blood pressure. The relationship was

Vika [28.1K]

Answer:

a) The 95% confidence interval for the mean is (-1.171, 11.717).

b) No, there is not enough evidence to support the claim that increasing the amount of calcium in our diet reduce blood pressure (at a 5% significance level).

Step-by-step explanation:

The data for both groups are:

Group 1 (calcium): 7 -4 18 17 -3 -5 1 10 11 -2

Group 2 (placebo): -1 12 -1 -3 3 -5 5 2 -11 -1 -3

The mean and standard deviation for Group 1 is:

$M_1=\dfrac{1}{10}\sum_{i=1}^{10}(7+(-4)+18+17+(-3)+(-5)+1+10+11+(-2))\\\\\\ M_1=\dfrac{50}{10}=5$

$s_1=\sqrt{\dfrac{1}{(n-1)}\sum_{i=1}^{10}(x_i-M)^2}\\\\\\$

$s_1=\sqrt{\dfrac{1}{9}\cdot [(7-(5))^2+(-4-(5))^2+...+(-2-(5))^2]}\\\\\\$

$s_1=\sqrt{\dfrac{1}{9}\cdot [(4)+(81)+(169)+(144)+(64)+(100)+(16)+(25)+(36)+(49)]}\\\\\\s_1=\sqrt{\dfrac{688}{9}}=\sqrt{76.44}\\\\\\s_1=8.743$

The mean and standard deviation for Group 2 is:

$M_2=\dfrac{1}{11}\sum_{i=1}^{11}((-1)+12+(-1)+(-3)+3+(-5)+5+2+(-11)+(-1)+(-3))\\\\\\ M_2=\dfrac{-3}{11}=-0.273$

$s_2=\sqrt{\dfrac{1}{(n-1)}\sum_{i=1}^{11}(x_i-M)^2}\\\\\\$

$s_2=\sqrt{\dfrac{1}{10}\cdot [(-1-(-0.273))^2+(12-(-0.273))^2+...+(-3-(-0.273))^2]}\\\\\\$

$s_2=\sqrt{\dfrac{1}{10}\cdot [(0.53)+(150.62)+...+(115.07)+(0.53)+(7.44)]}\\\\\\s_2=\sqrt{\dfrac{348.182}{10}}=\sqrt{34.82}\\\\\\s_2=5.901$

a) We have to calculate a 95% confidence interval for the difference between means, with a T-model.

The Group 1, of size n1=10 has a mean of 5 and a standard deviation of 8.743.

The Group 2, of size n2=11 has a mean of -0.273 and a standard deviation of 5.901.

The difference between sample means is Md=5.273.

$M_d=M_1-M_2=5-(-0.273)=5.273$

The estimated standard error of the difference between means is computed using the formula:

$s_{M_d}=\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}=\sqrt{\dfrac{8.743^2}{10}+\dfrac{5.901^2}{11}}\\\\\\s_{M_d}=\sqrt{7.644+3.166}=\sqrt{10.81}=3.288$

The degrees of freedom for this test are:

$df=n_1+n_2-1=10+11-2=19$

The critical t-value for a 95% confidence interval and 19 degrees of freedom is t=1.96.

The margin of error (MOE) can be calculated as:

$MOE=t\cdot s_{M_d}=1.96 \cdot 3.288=6.444$

Then, the lower and upper bounds of the confidence interval are:

$LL=M_d-t \cdot s_{M_d} = 5.273-6.444=-1.171\\\\UL=M_d+t \cdot s_{M_d} = 5.273+6.444=11.717$

The 95% confidence interval for the mean is (-1.171, 11.717).

b) This is a hypothesis test for the difference between populations means.

The claim is that increasing the amount of calcium in our diet reduce blood pressure.

Then, the null and alternative hypothesis are:

H_0: \mu_1-\mu_2=0\\\\H_a:\mu_1-\mu_2> 0

The significance level is 0.05.

The sample 1, of size n1=10 has a mean of 5 and a standard deviation of 8.743.

The sample 1, of size n1=11 has a mean of -0.273 and a standard deviation of 5.901.

The difference between sample means is Md=5.273.

$M_d=M_1-M_2=5-(-0.273)=5.273$

The estimated standard error of the difference between means is computed using the formula:

$s_{M_d}=\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}=\sqrt{\dfrac{8.743^2}{10}+\dfrac{5.901^2}{11}}\\\\\\s_{M_d}=\sqrt{7.644+3.166}=\sqrt{10.81}=3.288$

Then, we can calculate the t-statistic as:

$t=\dfrac{M_d-(\mu_1-\mu_2)}{s_{M_d}}=\dfrac{5.273-0}{3.288}=\dfrac{5.273}{3.288}=1.604$

The degrees of freedom for this test are:

$df=n_1+n_2-1=10+11-2=19$

This test is a right-tailed test, with 19 degrees of freedom and t=1.604, so the P-value for this test is calculated as (using a t-table):

$P-value=P(t>1.604)=0.063$

As the P-value (0.063) is bigger than the significance level (0.05), the effect is not significant.

The null hypothesis failed to be rejected.

There is not enough evidence to support the claim that increasing the amount of calcium in our diet reduce blood pressure.

4 0

3 years ago

SOMEONE PLEASE HELP ME!!! ILL GIVE YOU BRAINLIST <3 PLEASE THANK YOU

Kay [80]

<u>Step by Step Explanation:</u>

16. x - 4 = 4

Isolate the variable (x). Note the equal sign, what you do to one side, you do to the other. Add 4 to both sides:

x - 4 (+4) = 4 (+4)

x = 4 + 4

x = 8

17. a/4 = 4

Isolate the variable (a). Note the equal sign, what you do to one side, you do to the other. Multiply 4 to both sides:

(a/4)(4) = (4)(4)

a = (4)(4)

a = 16

18. y * 20 = 30

Isolate the variable (y). Note the equal sign, what you do to one side, you do to the other. Divide 20 from both sides.

(y *20)/20 = (30)/20

y = 30/20

y = 3/2 or 1.5

19. x/5 = 20

Isolate the variable (x). Note the equal sign, what you do to one side, you do to the other. Multiply 5 to both sides

(x/5)(5) = (20)(5)

x = (20)(5)

x = 100

3 0

3 years ago

This problem addresses some common algebraic errors. For the equalities stated below assume that x and y stand for real numbers.

weqwewe [10]

Answer:

The answers are:

a) $(x+y)^2 = x^2 + y^2$ is FALSE.

b) $(x+y)^2 = x^2 + 2xy + y^2$ is TRUE.

c) $\frac{x}{x+y}= \frac{1}{y}$ is FALSE.

d) $x-(x+y) = y$ is FALSE.

e) $\sqrt{x^2} = x$ is FALSE.

f) $\sqrt{x^2} = |x|$ is TRUE.

g) $\sqrt{x^2+4} = x+2$ is FALSE.

h) $\frac{1}{x+y} = \frac{1}{x} + \frac{1}{y}$ is FALSE.

Step-by-step explanation:

We can show that the FALSE statement are, in fact, false finding an example where the equality fails.

a) Take x=2 and y=3 and notice that (2+3)² = 25, while 2²+3²=4+9=13.

b) (x+y)² = (x+y)(x+y)=x²+xy+xy+y² = x² +2xy +y².

c) Take x=2 and y=3 and notice that 2/(2+3) = 2/5 which is different from 1/3.

d) Take x=2 and y=3 and notice that 2-(2+3) = 2-5=-3 which is different from 3. Recall that x-(x+y) = x-x-y=-y.

e) Take x=-2, and notice that [tax]\sqrt{(-2)^2} = \sqrt{4} = 2[/tex] which is different from -2.

f) The previous example illustrate why this is true.

g) Take x=1, and notice that $sqrt{1^2+4} = \sqrt{5}$ which is different from 3.

h) Take x=2 and y=3 and notice that 1/(2+3)=1/5 and 1/3+1/2 = 5/6.

3 0

3 years ago

In the figure above, what is the value of w?

Sholpan [36]

The answer would be c 110

7 0

3 years ago

if there are two angles that are supplementary,and the first angle has a measure of 137, what is the measure of the second angle

zvonat [6]

Answer:

43°

Step-by-step explanation:

supplementary angles sum to 180° , then

second angle + 137° = 180° ( subtract 137° from both sides )

second angle = 43°

4 0

2 years ago