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3 years ago

Comparing Methods to solving systems.

Mathematics

1 answer:

Natasha_Volkova [10]3 years ago

3 0

Answer:

$x = - 1 \\ y = 1$

Step-by-step explanation:

$x - y = - 2$

$x = y - 2$

$7x + 2y = - 5$

$7(y - 2) + 2y = - 5 \\$

$7y - 14 + 2y = - 5$

$9y = 14 - 5$

$9y = 9$

$y = \frac{9}{9} = 1$

$x = y - 2 = 1 - 2 = - 1$

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The poll found that 38% of a random sample of 1012 American adults said they believe in ghosts. What is the lower bound for a 90

Brrunno [24]

Answer:

The lower bound for a 90% confidence interval for the percentage of all American adults who believe in ghosts is 0.3549

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

For this problem, we have that:

$n = 1012, \pi = 0.38$

90% confidence level

So $\alpha = 0.1$ , z is the value of Z that has a pvalue of $1 - \frac{0.1}{2} = 0.95$ , so $Z = 1.645$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.38 - 1.645\sqrt{\frac{0.38*0.62}{1012}} = 0.3549$

The lower bound for a 90% confidence interval for the percentage of all American adults who believe in ghosts is 0.3549

6 0

4 years ago

Solve the system of linear equations by multiplying. Check the answer by graphing the system of equations. –2x + 2y = 10 -4x + 5

kari74 [83]

Answer:

x=2, y=7 (2,7)

Explanation:

Solve for the first variable in one of the equations, then substitute the result into the other equation.

8 0

3 years ago

The parking lot had 1.5 times as many trucks as cars. After 45 more cars came to the parking lot and 12 trucks left, there were

Harlamova29_29 [7]

Answer:

Total number of cars in the parking lot are 80.

Step-by-step explanation:

Let the number of cars = x and the number of trucks = y

Since, there are 1.5 times many cars than the truck, we get,

Number of cars = 1.5 time number of trucks

i.e. $y=1.5x$

Also, it is given that when 45 cars were added in the lot, 12 trucks left the parking lot.

So, we get,

Number of cars + 45 = Number of trucks - 12

i.e. $x+45=1.5x-12$

Finally, there are 17 cars more than the trucks.

We have the required equation, $x+45=1.5y-12+17$

i.e. $x+45=1.5x+5$

i.e. $45-5=1.5x-x$

i.e. $40=0.5x$

i.e. x= 80

Thus, the total number of cars in the parking lot are 80.

7 0

4 years ago

Suppose f(x) = x2 and g(x) = (4x)2. Which statement best compares the graph of g(x) with the graph of f(x)?

Paha777 [63]

Answer:

Option C

Step-by-step explanation:

Given: Functions $f(x) = x^2$ and $g(x)=(4x)^2$

Now, if we compare the both equation we get,

$g(x) = 4f(x)$ as $g(x) = 4(4x^2)=16x^2=(4x)^2=f(x)$

This means that the value of g(x) is 4 times the value of f(x). So the graph of g(x) is the graph of f(x) vertically stretched by a factor of 4.

The graph shown below confirms the conclusion.

Therefore, Option C is correct.

The graph of g(x) is the graph of f(x) vertically stretched by a factor of 4.

4 0

4 years ago

Read 2 more answers

-(4+h)=3h solve please

docker41 [41]

Answer:

h = -1

Step-by-step explanation:

- (4 + h) = 3h

- 4 - h = 3h

- h - 3h = 4

- 4h = 4

- h = 4/4

- h = 1

h = - 1

4 0

3 years ago

Read 2 more answers