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Soloha48 [4]
3 years ago
8

The following data represent the pH of rain for a random sample of 12 rain dates in Tucker County, West Virginia. A normal proba

bility plot suggests the data could come from a population that is normally distributed. A boxplot indicates there are no outliers
4.58 5.72 4.77 4.76 5.19 5.05 4.80 4.77 4.75 5.02 4.74 4.56 35
(a) Determine a point estimate for the population mean pH of
(b) Construct and interpret a 95% confidence interval for the mean
(c) Construct and interpret a 99% confidence interval for the mean
(d) What happens to the interval as the level of confidence is rainwater in Tucker County pH of rainwater in Tucker County, West Virginia. pH of rainwater in Tucker County, West Virginia. increased? Explain why this is a logical result.
Mathematics
1 answer:
Sphinxa [80]3 years ago
3 0

Answer:

Step-by-step explanation:

n = 12

Mean = (4.58 + 5.72 + 4.77 + 4.76 + 5.19 + 5.05 + 4.80 + 4.77 + 4.75 + 5.02 + 4.74 + 4.56)/12 = 4.8925

Standard deviation = √(summation(x - mean)²/n

Summation(x - mean)² = (4.58 - 4.8925)^2 + (5.72 - 4.8925)^2 + (4.77 - 4.8925)^2 + (4.76 - 4.8925)^2 + (5.19 - 4.8925)^2 + (5.05 - 4.8925)^2 + (4.80 - 4.8925)^2 + (4.77 - 4.8925)^2 + (4.75 - 4.8925)^2 + (5.02 - 4.8925)^2 + (4.74 - 4.8925)^2 + (4.56 - 4.8925)^2 = 1.122225

Standard deviation = √(1.122225/12

s = 0.31

a) Point estimate = sample mean = 4.8925

Confidence interval is written in the form,

(Sample mean - margin of error, sample mean + margin of error)

Margin of error = z × s/√n

Where

From the information given, the population standard deviation is unknown and the sample size is small, hence, we would use the t distribution to find the z score

In order to use the t distribution, we would determine the degree of freedom, df for the sample.

df = n - 1 = 12 - 1 = 11

b) Since confidence level = 95% = 0.95, α = 1 - CL = 1 – 0.95 = 0.05

α/2 = 0.05/2 = 0.025

the area to the right of z0.025 is 0.025 and the area to the left of z0.025 is 1 - 0.025 = 0.975

Looking at the t distribution table,

z = 2.201

Margin of error = 2.201 × 0.31/√12

= 0.197

95% confidence interval = 4.8925 ± 0.197

Upper limit = 4.8925 + 0.197 = 5.0895

Lower limit = 4.8925 - 0.197 = 4.6955

We are 95% confident that the population mean of the rain water ph lies between 4.6955 and 5.0895

c) For 99% confidence level, z = 3.106

Margin of error = 3.106 × 0.31/√12

= 0.278

99% confidence interval = 4.8925 ± 0.278

Upper limit = 4.8925 + 0.278 = 5.1705

Lower limit = 4.8925 - 0.278 = 4.6145

We are 99% confident that the population mean of the rain water ph lies between 4.6145 and 5.1705

d) The interval gets wider as the confidence level is increased. This is logical since the test score is higher for 99% and therefore, increases the range of values. Since we want to be more confident, the range of values must be extended.

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The sum of 444 consecutive integers is 326326326.<br> What is the second number in this sequence?
Nookie1986 [14]

Answer:

82

Step-by-step explanation:

Let's first figure out what the first number is and use that to solve for the next. The problem states that the numbers are consecutive. So the 2nd number word be 1 plus the first.

The sum of 4 consecutive numbers:

1st = x

2nd = x + 1

3rd = x + 2

4th = x + 3

The sum of 4 consecutive number is 326.

1st + 2nd + 3rd + 4th = 326

x + (x + 1) + (x + 2) + (x + 3)  = 326

Combine like terms:

4x + 6 = 326

Then we subtract 6 from both sides to isolate 4x:

4x + 6 - 6 = 326 - 6

4x = 320

Then we divide both sides by 4 to isolate x:

4x/4 = 320/4

x = 80

So the first number is 79

Now to get the second, let's just add 1.

80 + 1 = 81

Let's check if our answer would be correct:

80 + 81 + 82 + 83

= 326

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Answer:

the exact answer would be 651

Step-by-step explanation:

if you were to estimate I would say you should probably round up to 700

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Given the figure, if ∠ABC is 20° and C is the center of the circle, what is the measure of the central angle ∠ACB? A) 40° B) 70°
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Answer:

D) 140°

Step-by-step explanation:

The total number of degrees in a triangle is 180. Since both sides of the triangle are the radius of the circle, the triangle is isosceles. Therefore the two opposite angles are equal. Thus, the central angle is 180° − 2(20°) = 140°.

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Mrs. Jones has a local bakery. Last week this expression shows how many peanut butter cupcakes she baked. 5 (2x -4) + 3(3 + 4x)
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Answer:

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B. 121 cupcakes

Step-by-step explanation:

Part A:

The simplified form of the expression is

5(2x-4)+3(3+4x)

(10x-20)+(9+12x)

(10x+12x)+(9-20)

22x-11

Part B:

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22x-11

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