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3 years ago

2. State if the following is an observational study, a survey, or an experiment, and give a reason for your answer.

Mathematics

1 answer:

omeli [17]3 years ago

8 0

Answer:

If Ken wants to compare how many hours a week sixth graders spend doing mathematics homework to how many hours a week that eleventh graders spend doing mathematics homework and randomly selects ten sixth graders and ten eleventh graders and records how many hours each student spent on mathematics homework in a certain week then this is an observational study.

Step-by-step explanation:

An observational study depends on the data set statistical analysis, researchers do not manipulate any variable to reach conclusions. They design question-measurement to collect information without trying to affect their answers.

A survey is part of an observational study assessed on a sample population through controlled sample questions to collect specific data asking determined people and the response variable is the number of correct answers collected which are not influenced either.

In a controlled experiment, the researcher manipulates the sample population grouping people to assign them with some treatment or to do an specific task. Different groups are formed and assigned with different tasks to get the information wanted or to know proportion of the population in certain task.

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ANEK [815]

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3 years ago

In a class of 22 students, 13 have a brother and 15 have a sister. There are 3 students who do not have any siblings. What is th

Aneli [31]

Answer:

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Step-by-step explanation:

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2 years ago

The sum of 5 consecutive numbers is -5. What is the largest out of the numbers?

xxTIMURxx [149]

We can say that x is the largest number.

So the sum is x + (x - 1) + (x - 2) + (x - 3) + (x - 4) = -5

Now solve for x:

x + x + x + x + x - 1 - 2 - 3 - 4 = -5

5x - 10 = -5

5x = 5

x = 1

So the largest number is 1.

Check: 1 + 0 + -1 + -2 + -3 = -2 + -3 = -5 so 1 is correct.

3 0

3 years ago

Find the oth term of the geometric sequence 7, 14, 28, ...

yaroslaw [1]

Answer:

The nth term of the geometric sequence 7, 14, 28, ... is:

$a_n=7\cdot \:2^{n-1}$

Step-by-step explanation:

Given the geometric sequence

7, 14, 28, ...

We know that a geometric sequence has a constant ratio 'r' and is defined by

$a_n=a_1\cdot r^{n-1}$

where a₁ is the first term and r is the common ratio

Computing the ratios of all the adjacent terms

$\frac{14}{7}=2,\:\quad \frac{28}{14}=2$

The ratio of all the adjacent terms is the same and equal to

$r=2$

now substituting r = 2 and a₁ = 7 in the nth term

$a_n=a_1\cdot r^{n-1}$

$a_n=7\cdot \:2^{n-1}$

Therefore, the nth term of the geometric sequence 7, 14, 28, ... is:

$a_n=7\cdot \:2^{n-1}$

6 0

2 years ago

(a) Find a vector parallel to the line of intersection of the planes −4x+2y−z=1 and 3x−2y+2z=1.

valentinak56 [21]

Find the intersection of the two planes. Do this by solving for z in terms of x and y ; then solve for y in terms of x ; then again for z but only in terms of x.

-4x + 2y - z = 1 ==> z = -4x + 2y - 1

3x - 2y + 2z = 1 ==> z = (1 - 3x + 2y)/2

==> -4x + 2y - 1 = (1 - 3x + 2y)/2

==> -8x + 4y - 2 = 1 - 3x + 2y

==> -5x + 2y = 3

==> y = (3 + 5x)/2

==> z = -4x + 2 (3 + 5x)/2 - 1 = x + 2

So if we take x = t, the line of intersection is parameterized by

r(t) = ⟨t, (3 + 5t )/2, 2 + t⟩

Just to not have to work with fractions, scale this by a factor of 2, so that

r(t) = ⟨2t, 3 + 5t, 4 + 2t⟩

(a) The tangent vector to r(t) is parallel to this line, so you can use

v = dr/dt = d/dt ⟨2t, 3 + 5t, 4 + 2t⟩ = ⟨2, 5, 2⟩

or any scalar multiple of this.

(b) (-1, -1, 1) indeed lies in both planes. Plug in x = -1, y = 1, and z = 1 to both plane equations to see this for yourself. We already found the parameterization for the intersection,

r(t) = ⟨2t, 3 + 5t, 4 + 2t⟩

3 0

2 years ago