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iogann1982 [59]

2 years ago

14

Kate bought $23.40 worth of two types of bird seed. Thistle bird seed sells for $1.60 per pound and wild bird seed sells for $0.

95 per pound. If she bought 12 pounds of wild bird seed, write and solve a linear equation to find the amount of thistle bird seed she purchased.

1 answer:

earnstyle [38]2 years ago

6 0

Answer:

Ax+By=C and 7.5 lb of Thistle

Step-by-step explanation:

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Using the key below, classify each of the following descriptions of epidemiologicalstudies according to study type. In your answ

emmasim [6.3K]

Answer:

Answers are written in BOLD in the explanation below.

Step-by-step explanation:

(A) The study was done in 1975 but the 825 insulation workers were employed or worked between 1941 and 1944. This makes the study a RETROSPECTIVE study.

There is an exposed group (insulation workers) and an unexposed group (coworkers who did not work with insulation). In addition (an additional reason), the study begins with exposed patients and then unexposed patients. These reasons make it a COHORT study.

This study is also an ANALYTICAL study, as the investigators made a postulation, based on analysis of the number of lung cancer deaths among non-insulation workers and the number of lung cancer deaths among insulation workers.

This is also an ECOLOGICAL study, as study results are applicable only at population level.

(B) This is an EXPERIMENTAL study, as the researcher/investigator seeks new knowledge by selecting groups to derive certain data from; in a step by step manner.

Due to the random selection of subjects (volunteers) and random assignment of them to the two groups, this is a RANDOMIZED TRIAL.

The presence of similar experimental and control groups (all volunteers/subjects have osteoarthritis) is a key feature of RANDOMIZED CONTROLLED TRIAL.

After the selection of subjects, experiment of pain levels was conducted for some months (up to a year). This makes the study a PROSPECTIVE study because there was follow-up on the groups, to see who develops the outcome of interest.

The fact that there was no experimental report after 9 and 12 months of follow-up is another key feature of the RCT because in a RCT, the investigator often faces issues like dropout and noncompliance of subjects.

(C) This is a COMMUNITY TRIAL study because two cities/communities are experimented on.

This is also an EXPERIMENTAL study. The fact that both cities have similar demographic profiles and air pollution levels confirms a key feature of experimental studies. There is a 2-year follow-up. This is another reason why the study is experimental and PROSPECTIVE.

(D) This is an OBSERVATIONAL study. This is because already available data was collected and simply looked upon or observed, to know if chewing tobacco was a significant risk factor for stomach cancer.

The data is historical data, hence this is a RETROSPECTIVE study.

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GOODLUCK!

4 0

3 years ago

About 17% of the population of a large country is allergic to pollen. if two people are randomly selected, what is the probabi

natulia [17]

P( both allergic) = 0.17*0.17 = 0.0289

P(at least one is allergic) = 1 - P(neither are allergic) = 1 - 0.83^2 = 0.311

8 0

3 years ago

A ceiling light has a cross-section in the shape of a parabola. The parabola is 24 cm wide and 9 cm deep. The lightbulb is locat

Sedbober [7]

Answer:

4 cm

Step-by-step explanation:

The equation of a parabola with its vertex at the origin can be written as ...

y = 1/(4p)x^2

The problem statement tells us that one point on the parabola is (x, y) = (12, 9). We can put these values into the equation and solve for p, the distance from the focus to the vertex.

9 = 1/(4p)(12^2)

9×4/144 = 1/p = 1/4 . . . . . . . . multiply by the inverse of the coefficient of 1/p

Then p = 4, and the bulb is 4 cm from the vertex.

4 0

3 years ago

Suppose $p(x)$ is a monic cubic polynomial with real coefficients such that $p(3-2i)=0$ and $p(0)=-52$. determine $p(x)$ (in exp

Maslowich

If $p(3-2i)=0,$ then complex number $3-2i$ is a root of cubic polynomial.

If polynomial has real coefficients, then conjugated $3+2i$ is also a root of polynomial.

Then the polynomial will be of a form

$p(x)=(x-(3-2i))(x-(3+2i))(x-a).$

Since $p(0)=-52,$ then

$-52=(0-(3-2i))(0-(3+2i))(0-a),\\ \\-52=(2i-3)(3+2i)a,\\ \\-52=(4i^2-9)a,\\ \\-52=(-4-9)a,\\ \\-13a=-52,\\ \\a=4.$

Therefore,

$p(x)=(x-(3-2i))(x-(3+2i))(x-4),\\ \\p(x)=(x^2-6x+13)(x-4),\\ \\p(x)=x^3-10x^2+37x-52.$

3 0

2 years ago

A regression model involved 18 independent variables and 200 observations. The critical value of t for testing the significance

Evgen [1.6K]

Answer:

The correct answer to the following question will be Option d (181 degrees of freedom).

Step-by-step explanation:

The given values are:

Regression model,

n = 200

Observations,

p = 18

Now,

⇒ $n-p-1$

On putting the estimated values, we get

⇒ $200-18-1$

⇒ $181$

So that the correct choice will be "181 degrees of freedom".

6 0

2 years ago