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SIZIF [17.4K]
3 years ago
13

For a set of data, x is the explanatory variable. Its mean is 8.2, and its standard deviation is 1.92. For the same set of data,

y is the response variable. Its mean is 13.8, and its standard deviation is 3.03. The correlation was found to be 0.223.
Select the correct slope and y-intercept for the least-squares line.
a. Slope = -0.35
y-intercept = -10.9
b. Slope = -0.35
y-intercept = 10.9
c. Slope = 0.35
y-intercept = -10.9
d. Slope = 0.35
y-intercept = 10.9
Mathematics
1 answer:
aniked [119]3 years ago
4 0

Answer:

d. Slope = 0.35

y-intercept = 10.9

Step-by-step explanation:

The computation is shown below:

Data given in the question

Mean \bar X = 8.2

The standard deviation  of x = \sigma = 1.92

Mean \bar Y = 13.8

The standard deviation  of y = \sigma = 3.03

The correlation = r = 0.223

Based on the above information,

As we know that

The slope is

b = r \frac{\sigma y }{\sigma x} \\\\ = (0.223) (\frac{3.03}{1.92} \\\\ = (0.223) (1.578125)

= 0.3519

Now the y-intercept is

a = \bar Y - b \bar X \\\\

= 13.8  - (0.351922) 8.2

= 13.8 - 2.88579

= 10.91

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Helga [31]

Answer:

The sample size needed is 2401.

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}.

The margin of error of the interval is:

M = z\sqrt{\frac{\pi(1-\pi)}{n}}

95% confidence level

So \alpha = 0.05, z is the value of Z that has a pvalue of 1 - \frac{0.05}{2} = 0.975, so Z = 1.96.

Estimate the sample size needed if no estimate of p is available so that the confidence interval will have a margin of error of 0.02.

We have to find n, for which M = 0.02.

There is no estimate of p available, so we use \pi = 0.5

M = z\sqrt{\frac{\pi(1-\pi)}{n}}

0.02 = 1.96\sqrt{\frac{0.5*0.5}{n}}

0.02\sqrt{n} = 1.96*0.5

\sqrt{n} = \frac{1.96*0.5}{0.02}

(\sqrt{n})^{2} = (\frac{1.96*0.5}{0.02})^{2}

n = 2401

The sample size needed is 2401.

7 0
3 years ago
Read 2 more answers
There are two numbers whose sum is 64. The larger number subtracted from 4 times the smaller number gives 31. Find the numbers.
Pani-rosa [81]

There are two numbers whose sum is 64. The larger number subtracted from 4 times the smaller number gives 31. Then the numbers are 45 and 19

<h3><u>Solution:</u></h3>

Given that, There are two numbers whose sum is 64.  

Let the number be a and b in which a is bigger.

Then, a + b = 64 ------ eqn (1)

The larger number subtracted from 4 times the smaller number gives 31.  

4 x b – a = 31  

4b – a = 31 ----- eqn (2)

We have to find the numbers.

So, from eqn (2)

a = 4b – 31

Subatitute a in (1)

4b – 31 + b = 64

On solving we get

5b  = 64 + 31  

5b = 95

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So, b = 19, then eqn 1

a + 19 = 64

On simplification,

a = 64 – 19

a = 45  

Hence, the two numbers are 45 and 19

3 0
3 years ago
A function models the growth of a sample starting with 40 bacteria with the ability to double every two hours. Which graph
natima [27]

Answer:

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The graph is in the image attached

Step-by-step explanation:

The function that models this growth is an exponencial function, that can be described with the following equation:

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Where a is the inicial value, b is the rate of growth, x is the time and n is the relation between the time and the rate (the rate occurs for every two hours, so n = 2).

Then, using a = 40, r = 2 and n = 2, we have:

y = 40 * 2^(x/2)

If we plot this function, we have the graph shown in the image attached,

It is an exponencial graph, where the value of y increases very fast in relation to the increase of x.

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Alex17521 [72]

Answer:

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