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SOVA2 [1]
4 years ago
15

20 POINTS!!! Mr. Moore is installing new work benches in the wood shop. He wants the height of the benches to be best for studen

ts standing and working on projects. He decides to use the mean height of the students in the school as a guide. The school has 6th, 7th, and 8th grade students. Rather than using the heights of all the students in the school, he decides to take a sample of students.
A: Suppose Mr. Moore decides to use 20 seventh graders as the sample. Is this sample a random sample? Explain your reasoning.

B: Mr. Moore decides to use a random number generator to select 20 students from the school. Suppose that when choosing 20 students using the random generator on the graphing calculator, Mr. Moore’s sample is all eighth graders. Does that mean the sample is not a random sample? Explain your reasoning.
Mathematics
2 answers:
liubo4ka [24]4 years ago
6 0

A: Suppose Mr. Moore decides to use 20 seventh graders as the sample. Is this sample a random sample? Explain your reasoning.

Ans: No, because he only chose the seventh graders which is invalid since he wants to have to use the mean height which involves the 6th, 7th and 8th graders.

B: Mr. Moore decides to use a random number generator to select 20 students from the school. Suppose that when choosing 20 students using the random generator on the graphing calculator, Mr. Moore’s sample is all eighth graders. Does that mean the sample is not a random sample? Explain your reasoning.

Ans: No, it is still a random sample. Since he is using a random generator, there is a possibility that the random generator would pick all students from the 8th grade. Unlike the first one, the random generator is not biased towards any grade, it is just a coincidence.

Viktor [21]4 years ago
3 0

Answer:

A) That's not a random sample because everyone doesn't have an equal chance of being selected

B) It is a random sample. All from eight grade is just a coincidence (which is very unlikely)

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The extremes in the proportion 3/4=15/20 are
ollegr [7]

<span>In the form of a/b = c/d in proportions in math, the outer terms are called the extremes and the inner terms are called means. In the given 3/4 = 15/20, the outer terms or the extremes are 3 and 20.</span>

3 0
3 years ago
Suppose babies born in a large hospital have a mean weight of 3316 grams, and a standard deviation of 324 grams. If 83 babies ar
Anuta_ua [19.1K]

Answer: 0.129

Step-by-step explanation:

Let \overline{X} denotes a random variable that represents the mean weight of babies born.

Population mean : \mu= \text{3316 grams,}

Standard deviation: \text{324 grams}

Sample size = 83

Now, the probability that the mean weight of the sample babies would differ from the population mean by greater than 54 grams will be :

P(|\mu-\overline{X}|>54)=1-P(\dfrac{-54}{\dfrac{324}{\sqrt{83}}}

hence, the required probability =  0.129

5 0
4 years ago
a disc is thrown into the air with an upward velocity of 62 ft/s.its height h in feet after t seconds is given by the function h
Korolek [52]
Given that the height of the disc is modeled by the function:
h=-16t^2+20t+6
a] The maximum height will be as follows:
At maximum height:
h'(t)=0
from h(t)
h'(t)=-32t+20=0
thus
t=20/32
t=5/8 sec
thus the maximum height will be:
h(5/8)=-16(5/8)^2+20(5/8)+6
          =12.25 ft

b] <span>How long will it take the disc to reach the maximum height?
</span>time taken to reach maximum height will be:
from h(t)
h'(t)=-32t+20=0
thus
t=20/32
t=5/8 sec
thus time taken to reach maximum height is t=5/8 sec

c]<span>How long does it take for the disc to be caught 3 feet off the ground?
</span>h(t)=-16t^2+20t+6
but
h(t)=3
thus
3=-16t^2+20t+6
solving for t we get:
0=-16t^2+20t+3
factoring the above we get:
t=5/8-/+√37/8
t=-1.5256 or 2.776
since there is no negative time we pick t=2.776
Hence time taken for the disc to be caught 3 ft from the ground is 2.776 ft

3 0
3 years ago
an airplane travels 5424 km against the wind in 8 hours and 6624 km with the wind in the same amount of time. what is the rate o
liq [111]

Answer:

The rate of the plane is 753 km/h while the rate of the wind is 75km/h

Step-by-step explanation:

Here in this question, we are interested in calculating the rate of the plane in still air and the rate of the wind.

Since we do not know these rates, we shall be representing both using variables.

Let’s represent the rate of the plane in still air by x kmph while the rate of the wind be represented by y kmph

Now, for us to calculate the speed of the plane while it travels against the wind, that would be the speed of the plane in still air minus the speed of the wind.

Mathematically, that would be (x-y) kmph

Now the speed of the plane while it travels with the wind would be its speed in still air plus the speed of the wind.

Mathematically, that would be;

(x + y) kmph

From the question;

The plane journeyed 5424 km against the speed in 8 hours, this means that its speed will be 5424/8 = 678 kmph

Thus, that means;

x -y = 678 •••••••(i)

Now, traveling with the wind , its speed will be ;

6624/8 = 828 kmph

Thus;

x + y = 828 kmph •••••••(ii)

So we have two equations to solve simultaneously;

Let’s add both together;

x -y + x + y = 828+ 678

2x = 1,506

x = 1506/2

x = 753 kmph

From ii

x + y = 828

y = 828 - x

y = 828 - 753

y = 75 kmph

5 0
3 years ago
7 less than 3 times a number is -81. Find the number
IrinaK [193]

Answer:

-24.6 repeating

Step-by-step explanation:

4 0
4 years ago
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