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Archy [21]
2 years ago
9

Change 7 out of 50 into a percentage and change 18 out of 20 into a percentage

Mathematics
1 answer:
Ksivusya [100]2 years ago
3 0
7/50 = 0.14
0.14 x 100 = 14
14%

18/20 = 0.9
0.9 x 100 = 90
90%
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3 years ago
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Allen�s hummingbird (Selasphorus sasin ) has been studied by zoologist Bill Alther A small group of 15 Allen� s hummingbirds has
Bogdan [553]

Answer:

1) 80% CI: [3.04; 3.26]gr

d= 0.11

2) n= 28 hummingbirds

Step-by-step explanation:

Hello!

The study variable of this experiment is:

X: the weight of a hummingbird. (gr)

And it has a normal distribution, symbolically: X~N(μ;σ²)

And (I hope I got it correctly) its population standard deviation is σ= 0.33

There was a sample of n= 15 hummingbirds taken, its sample mean X[bar]= 3.15 gr

1) You need to construct an 80% Confidence Interval for the population mean of the hummingbird's weight.

Since the study variable has a normal distribution, you can use either the standard normal distribution or the Student's t distribution. Both are useful to estimate the population mean. Since the population standard variance is known, the best choice is the Standard normal.

Z= <u> X[bar] - μ </u>~ N(0;1)

       σ/√n

The formula for the interval is:

X[bar] ± Z_{1- \alpha /2} * (σ/√n)

Z_{1- \alpha /2}= Z_{0.90} = 1.28

3.15 ± 1.28 * (0.33/√15)

[3.04; 3.26]gr

The margin of error (d) of a confidence interval is hal its amplitude (a)

a= Upper bond - Lower bond

d= (Upper bond - Lower bond)/2

d= \frac{(3.26-3.04)}{2} = 0.11

2) You need to calculate a sample size for a 80% Confidence interval for the average weight of the hummingbirds with a margin of error of d= 0.08

As I said before, the margin of error is half the amplitude of the interval, the formula you use to estimate the population mean has the following structure:

"point estamator" ± "margin of error"

Then the margin of error is:

d= Z_{1- \alpha /2} * (σ/√n)

Now what you have to do is rewrite the formula based on the sample size

d= Z_{1- \alpha /2} * (σ/√n)

\frac{d}{Z_{1- \alpha /2}}= σ/√n

√n * \frac{d}{Z_{1- \alpha /2}}= σ

√n = σ * \frac{Z_1- \alpha /2}{d}

n = (σ * \frac{Z_1- \alpha /2}{d})²

n=  (0.33 * \frac{1.28}{0.08})²

n= 27.8784 ≅ 28 hummingbirds.

I hope it helps!

4 0
3 years ago
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shepuryov [24]

Answer:

(-9, 10)

Step-by-step explanation:

The location of the midpoint of a line with endpoint at (x_1,y_1) and (x_2,y_2) is given as (x, y). The location of x and y are:

x = \frac{x_1+x_2}{2},y=\frac{y_1+y_2}{2}

Given the endpoint (9,8) and Midpoint (0,9), the location of the other endpoint can be gotten from:

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Hence the endpoint is at (x2, y2) which is at (-9, 10)

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The word greatest in a word problem tells you to do GCF and the word least in a problem means to use the LCM
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Paid $1,000 in interest on a loan of $10,000 for a
Lorico [155]

Answer:

R = 2 % per annum.

Step-by-step explanation:

SI = (P*T*R) /100

$1000 = ($10000 * 5 yrs *Rate) /100

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3 years ago
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