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Marat540 [252]
3 years ago
9

The DNR is planning a study to determine whether breakwaters help decrease erosion at a large lake. They divide the shoreline in

to 100-foot plots, installing some with breakwaters and some without. However, the east and west shorelines of this lake receive very different wave patterns due to the wind. The DNR suspects this will affect the responses to the breakwaters. Because of this, the DNR plans to treat each shoreline as a different group. This study is an example of__________.
(A) An uncontrolled experiment
(B) A blocked design experiment.
(C) A matched pairs experiment.
(D) A stratified random sample
(E) A randomized observational study
Mathematics
1 answer:
jekas [21]3 years ago
3 0

Answer:

Option B: A blocked design experiment

Step-by-step explanation:

A blocked design experiment takes into cognizance that there is one factor or variable that is of primary interest. However, there are also several other nuisance factors that may affect the measured result. The experimenter will have to look into which nuisance factors are important enough to keep track of or control, if possible, during the experiment which in this case is "However, the east and west shorelines of this lake receive very different wave patterns due to the wind". This can be controlled to reduce the contribution of experimental errors thus treating each shoreline as a different group.

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Area of a triangle (picture provided)
nignag [31]

Answer:

C

Step-by-step explanation:

The area of triangles is 1/2 x b x h.

Plug them in!

1/2 x 24 x 35

Simplify.

12 x 35

420 square inches

6 0
3 years ago
Which sum or difference identity would you use to verify that cos (180° - q) = -cos q?
Phantasy [73]

Answer:

\cos (a-b)=\cos a \cos b+\sin a \sin b

Step-by-step explanation:

 Given : \cos (180^{\circ}-q)=-\cos q

We have to write which identity we will use to prove the given statement.

Consider \cos (180^{\circ}-q)=-\cos q

Take left hand side of given expression \cos (180^{\circ}-q)

We know

\cos (a-b)=\cos a \cos b+\sin a \sin b

Comparing , we get, a= 180° and b = q

Substitute , we get,

\cos (180^{\circ}-q)=\cos 180^{\circ}  \cos (q)+\sin q \sin 180^{\circ}

Also, we know \sin 180^{\circ}=0 and \cos 180^{\circ}=-1

Substitute, we get,

\cos (180^{\circ}-q)=-1\cdot \cos (q)+\sin q \cdot 0

Simplify , we get,

\cos (180^{\circ}-q)=-\cos (q)

Hence, use difference identity to  prove the given result.

7 0
3 years ago
Read 2 more answers
Please answer! Explain all steps!
MatroZZZ [7]
We will be using the formulas:
speed=distance/time
time=distance/speed
distance=speed×time
First let's find out Diane's rate of swimming. We can measure this by finding the slope (y/x) of a given coordinate on the graph. One point is (10,15), so you do 15/10=1.5m/s
Now for Rick's rate of swimming, just take a pair of values from the table. 12.5/10=1.25m/s
By the way m/s is metres per second for this
So at a constant speed of 1.5m/s, Diane swam 150m in 150/1.5= 100 seconds, or 1 minute 40 seconds
And at a constant speed of 1.25m/s, Rick swam 150m in 150/1.25= 120 seconds, or 2 minutes.
So the difference between their two times is 20 seconds
7 0
3 years ago
Read 2 more answers
Quadrilateral ABCD​ is inscribed in this circle.
Svetllana [295]

Answer:

132°

Step-by-step explanation:

Quadrilateral ABCD is inscribed in a circle,

So, it is a cyclic quadrilateral.

Opposite angles of a cyclic quadrilateral are supplementary.

\implies \: x \degree + (3x - 12) \degree = 180 \degree \\  \\ \implies \: (4x - 12) \degree = 180 \degree \\  \\  \implies \: 4x - 12  = 180  \\  \\ \implies \: 4x   = 180  + 12 \\  \\ \implies \: 4x   = 192 \\  \\ \implies \: x   =  \frac{192}{4}  \\  \\ \implies \: x   = 48\\\\

(3x-12)° = (3*48 - 12)° = (144 - 12)° = 132°

\implies \: m\angle B   = 132\degree\\\\

5 0
2 years ago
Solve for h please and thank you
KonstantinChe [14]

Answer:

35° (I may be wrong)

Step-by-step explanation:

An isosceles triangle has an interior angle sum of 180° (like all triangles).

So...

180°-40°= 140°

And because we know that isoceles triangles and two congruent sides, we just have to divide 140° by 2.

140°÷2=70°

But the picture says 2h and h is a side so...

70°÷2=35°

4 0
3 years ago
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