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densk [106]
2 years ago
10

Can someone please help me on this I beg you please

Mathematics
1 answer:
ANEK [815]2 years ago
6 0

Answer:

b

Step-by-step explanation:

b

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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
ASAP can someone help me solve this problem​
sveta [45]

Answer:

Step-by-step explanation:

x° + y° = 180°

2y° - 0.5x° = 180°

y° = 108°

x° = 72°

3 0
3 years ago
What is the slope of the points<br> (-2,5) and (4,-6)?
notsponge [240]

Answer:

-11/6

Step-by-step explanation:

6 0
2 years ago
I need some one to do this fast!!!
Kruka [31]
It’s 8 u cross multiply 7 and 1 then 1 and 56 and then divide 56 by 7
7 0
3 years ago
Let ​ f(x)=x2+5x−36 ​. Enter the x-intercepts of the quadratic function in the boxes.
san4es73 [151]
Rearrange:

Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation : 

                     x^2-5*x-(36)=0 

Step by step solution:<span> Step 1:</span> Trying to factor by splitting the middle term

<span> 1.1 </span>    Factoring <span> x2-5x-36</span> 

The first term is, <span> <span>x2</span> </span> its coefficient is 1.
The middle term is, <span> -5x </span> its coefficient is  - 5.
The last term, "the constant", is <span> -36 </span>

Step-1: Multiply the coefficient of the first term by the constant <span> <span> 1</span> • -36 = -36</span> 

Step-2: Find two factors of  -36  whose sum equals the coefficient of the middle term, which is - 5.

<span><span>     -36   +   1   =   -35</span><span>     -18   +   2   =   -16</span><span>     -12   +   3   =   -9</span><span>     -9   +   4   =   -5   That's it</span></span>


Step-3: Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  -9  and  4 
                     <span>x2 - 9x</span> + 4x - 36

Step-4: Add up the first 2 terms, pulling out like factors :
                    x • (x-9)
              Add up the last 2 terms, pulling out common factors :
                    4 • (x-9)
Step-5: Add up the four terms of step 4 :
                    (x+4)  •  (x-9)
             Which is the desired factorization

<span>Equation at the end of step  1  :</span> (x + 4) • (x - 9) = 0 <span>Step  2  :</span>Theory - Roots of a product :

<span> 2.1 </span>   A product of several terms equals zero.<span> 

 </span>When a product of two or more terms equals zero, then at least one of the terms must be zero.<span> 

 </span>We shall now solve each term = 0 separately<span> 

 </span>In other words, we are going to solve as many equations as there are terms in the product<span> 

 </span>Any solution of term = 0 solves product = 0 as well.

Solving a Single Variable Equation :

<span> 2.2 </span>     Solve  :    x+4 = 0<span> 

 </span>Subtract  4  from both sides of the equation :<span> 
 </span>                     x = -4 

Solving a Single Variable Equation :

<span> 2.3 </span>     Solve  :    x-9 = 0<span> 

 </span>Add  9  to both sides of the equation :<span> 
 </span>                     x = 9 

6 0
3 years ago
Read 2 more answers
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