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kirill [66]
2 years ago
10

Alice wants to prove to her parents that listening to music while she does her homework will help her get better grades. She dec

ides to ask 25 of her friends if they listen to music while they do their homework and what their grades are. She finds that her friends who have high grades also listen to music while they do their homework. She tells her parents that she has proven that listening to music while doing homework will cause her grades to improve. What mistake has Alice made?
A) She did not separate her friends into different groups, and she didn't apply a treatment.
B) She did not separate her friends into different groups, and she used a survey to collect data.
Mathematics
1 answer:
Leona [35]2 years ago
8 0
The answer would be A.

Explanation: First off, she did not separate her friends into different groups. Secondly, she only got information from the students who listen to music. She should've gotten information from the students who don't listen to music in order to compare her results. She needed to make the survey equal meaning that, she needed to survey the students who listen to music and the ones that don't.
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A biologist is studying the growth of a particular species of algae. She writes the following equation to show the radius of the
vitfil [10]

Let's solve for d.

fd=(7)(1.06)d

Step 1: Add -7.42d to both sides.

df+−7.42d=7.42d+−7.42d

df−7.42d=0

Step 2: Factor out variable d.

d(f−7.42)=0

Step 3: Divide both sides by f-7.42.

d(f−7.42)f−7.42=0f−7.42

d=0f−7.42

Answer:

d=0f−7.42

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4 0
1 year ago
Sales tax on an item is directly proportional to the cost of the item purchased. If the tax on a $600 item is $42, what is the s
Dafna11 [192]
Answer: $65.10

Step-by-step work:

1.Set the ratio
\frac{600}{42}  =  \frac{930}{x}
2.Cross-multiply
600x = 930(42)
600x = 39060
3.Divide to single out x
600x \div 600 = 39060 \div 600
x = 65.10


4 0
2 years ago
Ms. Canciano was putting ribbon around a bulletim broard. She used 28 inches of ribbon to go all the way around and knew that th
Nadya [2.5K]

Answer:

48 sq inches

Step-by-step explanation:

Given that,

Ribbon used around a bulletin broard is 28 inches

The length of her board is 6 inches

Let B is breadth of her board. 28 inches is perimeter. The perimeter of rectangle is given by :

P = 2(L+B)

28=2(6+B)

14=6+B

B=8 inches

The area of a rectangle is given by :

A = L×B

A = 8×6

A=48 sq inches

So, the area of her board is 48 sq inches

5 0
2 years ago
Investigate the following harvesting model both qualitatively and analytically. If a constant number h of fish are harvested fro
zalisa [80]

Answer:

a. The population does not become extinct in finite time.

Step-by-step explanation:

The model for the population of the fishery is

dP/dt = P(a-bP)-h, P(0) = P_0

If we rearrange and replace the constants we have:

\frac{dP}{P(7-P)-49/4} =dt\\\\-4 (\frac{dP}{4(P-7)P+49}) =dt\\\\-4 \frac{dP}{(2P-7)^2} =dt\\\\-4 \int\frac{dP}{(2P-7)^2} =\int dt\\\\-4(-\frac{1}{2(2P-7)})=t+C\\\\\frac{2}{2P-7}=t+C\\\\ t=0 \,\,\, P(0)=P_0\\\\\frac{2}{2P_0-7}=0+C\\\\C=\frac{2}{2P_0-7}

Now we can calculate if the population become 0 in any finite time

\frac{2}{2P-7}=t+\frac{2}{2P_0-7}\\\\\frac{2}{2*0-7}=t+\frac{2}{2P_0-7}\\\\-\frac{2}{7}=t+\frac{2}{2P_0-7}\\\\

To be a finite time, t>0

t=-\frac{2}{7}-\frac{2}{2P_0-7}=0\\\\-\frac{2}{2P_0-7}=\frac{2}{7}\\\\7-2P_0=7\\\\P_0=0

We can conclude that the only finite time in which P=0 is when the initial population is 0.

Because P0 is a positive constant, we can say that the population does not become extint in finite time.

5 0
2 years ago
Eli wants to plant 45 sunflower plants, 81 corn plants and 63 tomato plants in his garden. If he put the same number of plants i
nevsk [136]

Answer:

GCF

Step-by-step explanation:

Each row will have the same number of plants.  So we want to know what's the biggest number we can divide 45, 81, and 63 by.  That means we need to find the greatest common factor.  In this case, it's 9.  Each row can have at most 9 seeds.

4 0
2 years ago
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