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Alisiya [41]
3 years ago
8

Soil pH is an important variable in the design of structures that will contact the soil. Nine test samples of soil from a potent

ial construction site gave readings of
7.3 6.5 6.4 6.1 6.0 6.5 6.2 5.8 6.7
Assuming that soil pH is normally distributed, find the 90% lower confidence bound for the true average soil pH at the site.
Mathematics
1 answer:
natta225 [31]3 years ago
8 0

Answer:

90% lower confidence bound for the true average soil pH at the site is ≈ 6.13

Step-by-step explanation:

90% Lower Confidence bound can be calculated using M-ME where

  • M is the sample mean pH (6.39)
  • ME is the margin of error from the mean

And margin of error (ME)  can be calculated using the formula

ME=\frac{t*s}{\sqrt{N} } where

  • t is the corresponding statistic in the 90% confidence level (1.86)
  • s is the standard deviation of the sample PH's (0.42)
  • N is the sample size (9)

Using the numbers we get:

ME=\frac{1.86*0.42}{\sqrt{9} } ≈ 0.26

Then the 90% lower confidence bound for the true average soil pH at the site is 6.39 - 0.26 = 6.13

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A random sample of 12 men age 60-65 has a mean blood pressure of 142. 3 mmHg and a standard deviation of 20.8 mmHg. Construct a
Over [174]

Answer:

The 99% confidence interval = (126.93,157.67)

Step-by-step explanation:

The formula for Confidence Interval =

Mean ± z × Standard deviation /√n

Mean = 142. 3 mmHg

Standard deviation = 20.8 mmHg.

n = 12

Z score for 99% confidence interval = 2.56

Confidence Interval =

142.3 ± 2.56 × 20.8/√12

142.3 ± 2.56 × 6.0044427996

142.3 ± 15.371373567

Confidence Interval

= 142.3 - 15.371373567

= 126.92862643

≈ 126.93

142.3 + 15.371373567

= 157.67137357

≈ 157.67

Therefore, the 99% confidence interval = (126.93,157.67)

3 0
3 years ago
How far from the origin is the point (-5, -12)?
raketka [301]
The first question is (7)
8 0
3 years ago
Read 2 more answers
(x -1) = 26 = -4x <br> A. -7 5/7<br> B. 8<br> C. -7<br> D. -5
Volgvan
Based on the answer choices, we suspect you intend
.. (x -1) +26 = -4x

This simplifies to
.. x +25 = -4x
.. 25 = -5x . . . . . subtract x
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Selection D appears to be appropriate for the question we think you asked.
4 0
3 years ago
Pls help lol its a quiz
White raven [17]
I would say F cause a triangle sides add up to 180
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What is the volume and total surface area of a sphere with the radius 2.25in?
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The volume is 15.89625
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