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Talja [164]
3 years ago
11

a) Suppose that a random sample of size 80 has a sample mean of 1.69 ppb and a sample standard deviation of 0.25 ppb. Find a 95%

confidence interval for the PCB concentration.
Mathematics
1 answer:
lys-0071 [83]3 years ago
4 0

Answer: The confidence interval is 1.69ppb±0.055

Step-by-step explanation:

To find the confidence interval, first find the z* which is the appropriate z*-value related to the confidence interval of preference. As in this is 95%, z*-value = 1.96 (Note: The value is from the standard normal Z distribution).

With the z*-value, multiply by the division of the standard deviation and the square root of the sample size:

z*-value . σ/√n = 1.96 · \frac{0.25}{\sqrt{80} } = 0.055

The 95% confidence interval of the sample mean of 1.69 ppb is 1.69ppb±0.055ppb

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Can I get help? And please give the steps to how you got your answer.
lyudmila [28]

Answer:

D

Step-by-step explanation:

First, plot the points they gave you onto a graph (shown in the attached image). The slope is the rise (units up or down from a given point) over the run (units left or right from a given point).

So the slope is 6/4 because to get from the red point to the blue point, you rise 6, and run 4. And from blue to red you rise (remember rise goes up or down) 6 and run 4. 6/4 can be simplified to 3/2 so D is your answer :)

6 0
3 years ago
Read 2 more answers
What are the whole steps to get the answer for 4x -6=x +9?
lesantik [10]
First do -x then -x to 4x so you have 3x-6=9.
Add 6 to -6 to cancel it out, then add 6 to 9.
3x-6. Divide 3from x, divide 3from 6. X=2. Plz answer my question too plz
6 0
2 years ago
Read 2 more answers
the height of the Statue of Liberty is 92 m. This about .27 the height of the Hancock Building in Chicago. What is the approxima
GuDViN [60]

Hancock building * .27 = 92 m

divide each side by .27

Hancock building =92/.27

Hancock building =340.740(repeating)

Answer: the building is approximately 340.74 meters


4 0
2 years ago
On a rectangular soccer field, Sang is standing on the goal line 20 yards from the corner post. Jazmin is standing 99 yards from
Anna007 [38]
Okay, so Sang is standing 20 yards away from one corner, and Jazmin is standing 99 yards away from the same corner. If this is a rectangle (I like visuals, so I'll use them to explain), then:
               
                    99ft
      A  -------------------------  B
         |                              |
20 ft  |                              |
         |                              |
    C   --------------------------  D

The question is asking you to solve for the diagonal line between points C and B. If you imagine a line there, you actually have the rectangle split into two triangles. So if you have triangle ABC, side CB would be the longest line, or the hypotenuse. That means you can use the Pythagorean Theorem to solve the problem.

A^2 + B^2 = C^2
99^2 + 20^2 = C^2
9,801 + 400 = C^2
10,201 = C^2

Now you solve for the square root of 10,201 to get C.

sqr (10,201) = C
C = 101 yards

3 0
3 years ago
Ari borrowed $2000 and paid it back over 3 years. The simple interest rate was 2% annually. How much interest did ari pay over t
sukhopar [10]
If the interst rate is 2% per year and she paid it back after 3 years , it means she paid an extra 6% of $2000 just in interests.

Now we just need to find how much 6% is and add to 2000.

to discover the value of 6% of 2000 we can divide it by 100 ( to find 1%) and then multiply it by 6 ( to find 6%) :

2000 ÷ 100 = 20
1% = 20
6% = 20 × 6
6% = 120

Now add 120 to 2000 to find out how much she paid in total:
2000 + 120 = 2120

Awnser : She paid the total of $2120 over 3 years

I hope you understood my brief explanation. And please consider marking this awnser as Branliest. Thank you ! :)
6 0
3 years ago
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