Help please i don’t understand

Alina, Robert, and Makayla are on the student council at their high school.

Scilla [17]

Answer:

B. Write each student's name on a slip of paper and put the slips in a bag. Randomly draw a slip of paper. The student whose name is on the paper wins

7 0

3 years ago

Read 2 more answers

A study was conducted to measure the effectiveness of hypnotism in reducing pain. The measurements are centimeters on a pain sca

saul85 [17]

Answer:

The 95% confidence interval for the difference would be given by (-1.776;0.376)

We are 95% confidence that the true mean difference is between $-1.776 \leq \mu_d \leq 0.376$ . Since the confidence interval contains the value 0, we don't have enough evidence to conclude that hypnotism appear to be effective in reducing pain.

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".

Let put some notation

x=test value before , y = test value after

x: 6.4 2.6 7.7 10.5 11.7 5.8 4.3 2.8

y: 6.7 2.4 7.4 8.1 8.6 6.4 3.9 2.7

The differences defined as $d_i = y_i -x_i$ and we got:

d: 0.3, -0.2, -0.3, -2.4, -3.1, 0.6, -0.4, -0.1

We can calculate the mean and the deviation for the sample with the following formulas:

$\bar d=\frac{\sum_{i=1}^n d_i}{n}$

$s_d =\frac{\sum_{i=1}^n (d_i -\bar d)^2}{n-1}$

$\bar d=-0.7$ represent the sample mean for the difference

$\mu_d$ population mean (variable of interest)

$s_d$ =1.32 represent the sample standard deviation

n=8 represent the sample size

Confidence interval

The confidence interval for the mean is given by the following formula:

$\bar d \pm t_{\alpha/2} *\frac{s_d}{\sqrt{n}}$ (1)

In order to calculate the critical value t we need to find first the degrees of freedom, given by:

$df=n-1=8-1=7$

Since the Confidence is 0.95 or 95%, the value of alpha=0.05 and \alpha/2 =0.025, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,8)".And we see that $t_(\alpha/2)=2.306$

Now we have everything in order to replace into formula (1):

$-0.7-2.306\frac{1.32}{\sqrt{8}}=-1.776$

$-0.7+2.306\frac{1.32}{\sqrt{8}}=0.376$

So on this case the 95% confidence interval for the difference would be given by (-1.776;0.376)

We are 95% confidence that the true mean difference is between $-1.776 \leq \mu_d \leq 0.376$ . Since the confidence interval contains the value 0, we don't have enough evidence to conclude that hypnotism appear to be effective in reducing pain.

6 0

4 years ago

A florist has an order to make flower bouquets. The order calls for the use of 45 roses and 63 carnations. Each bouquet made wil

Pavel [41]

Answer:

Step-by-step explanation:

45÷x=

63÷x=

they can both be divided by 9.

45÷9=5

63÷9=7

so 9 bouquets each containing different amounts is 5 roses and 7 carnations to each bouquet. your answer is 9

5 0

3 years ago

Given the directrix of y = -1 and focus of (0, 3), which is the equation of the parabola?

guajiro [1.7K]

Answer:

$y=\dfrac{1}{8}x^2+1$

Step-by-step explanation:

Since the vertex is right between the vertex and the directrix, the y value of the vertex must be (3+(-1))/2=1. The x coordinate will just be the same as that of the focus, or in this case 0. This means that the vertex will be at (0,1). Since the graph opens toward the focus, it will be opening up, and since its vertex is at (0,1), it will have an equation of:

$y=\dfrac{1}{8}x^2+1$

Hope this helps!

3 0

3 years ago

An acute ∆ABC is rotated about a point and then dilated by a scale factor of 0.5 to produce ∆A’B’C’. Which statement correctly c

icang [17]

Answer:

Option given in the top right.

Step-by-step explanation:

If an acute triangle is rotated about a point,

- Angles of the transformed triangle remain unchanged.

If a triangle is dilated by a scale factor of $\frac{1}{2}$ ,

- Measure of sides of the image will be dilated by a scale factor of 0.5.

Therefore, statement that compares ΔABC to ΔA'B'C' will be,

The angle measures of the triangle A'B'C'are the same of those ΔABC, but the side length of the ΔA'B'C' half the size of those of ΔABC.

Option given in the top right is the answer.

5 0

3 years ago