Wendy did a survey of four bird parks and wrote the following observations:

Casey puts wrapping paper around a gift box. She wants to tie a ribbon

kkurt [141]

Well 12 inches is a foot so 24inches is 2 feet so there is a hint so 90 divided by 12 and there is part of it

3 0

3 years ago

How do you solve (7x + 5) - (3x + 2)

Korolek [52]

Answer:

x = 0.75

Step-by-step explanation:

Simplifying

(7x + -5) + -1(3x + -2) = 0

Reorder the terms:

(-5 + 7x) + -1(3x + -2) = 0

Remove parenthesis around (-5 + 7x)

-5 + 7x + -1(3x + -2) = 0

Reorder the terms:

-5 + 7x + -1(-2 + 3x) = 0

-5 + 7x + (-2 * -1 + 3x * -1) = 0

-5 + 7x + (2 + -3x) = 0

Reorder the terms:

-5 + 2 + 7x + -3x = 0

Combine like terms: -5 + 2 = -3

-3 + 7x + -3x = 0

Combine like terms: 7x + -3x = 4x

-3 + 4x = 0

Solving

-3 + 4x = 0

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '3' to each side of the equation.

-3 + 3 + 4x = 0 + 3

Combine like terms: -3 + 3 = 0

0 + 4x = 0 + 3

4x = 0 + 3

Combine like terms: 0 + 3 = 3

4x = 3

Divide each side by '4'.

x = 0.75

Simplifying

x = 0.75

6 0

2 years ago

Read 2 more answers

Your state is considering raising the legal age for consumption of alcoholic beverages to 21 years old. How large a sample size

julsineya [31]

Answer:

$n=\frac{0.5(1-0.5)}{(\frac{0.01}{2.58})^2}=16641$

And rounded up we have that n=16641

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{p(1-p)}{n}})$

Solution to the problem

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by $\alpha=1-0.99=0.01$ and $\alpha/2 =0.005$ . And the critical value would be given by:

$z_{\alpha/2}=-2.58, t_{1-\alpha/2}=2.58$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.01$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

For this case we can use as estimator for the proportion $\hat p =0.5$ , since we don't have any other previous info. And replacing into equation (b) the values from part a we got:

$n=\frac{0.5(1-0.5)}{(\frac{0.01}{2.58})^2}=16641$

And rounded up we have that n=16641

8 0

3 years ago

write a linear equation that intersects y=x^2 at two points. Then write a second linear equation that intersects y=x^2 at just o

Liula [17]

We know that $y = x^2$ is a parabola, concave up, with vertex in the origin $(0,0)$

So, we may use three horizontal lines for our purpose: any horizontal line above the x axis will intersect the parabola twice. The x axis itself intersects the parabola once on the vertex, while any horizontal line below the x axis won't intercept the parabola.

Here's the examples:

The horizontal line $y = 4$ intercepts the parabola twice: the system $y = x^2,\ y = 4$ is solved by $x^2=4 \implies x = \pm 2$
The horizontal line $y=0$ intercepts the parabola only once: the system is $y=x^2,\ y=0$ which yields $x^2=0\implies x=0$ which is a repeated solution
The horizontal line $y=-5$ intercepts the parabola only once: the system is $y=x^2,\ y=-5$ which yields $x^2=-5$ which is impossible, because a squared number can't be negative.