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The accompanying summary data on CeO2 particlesizes (nm) under certain experimental conditions wasread from a graph in the article 鈥淣anoceria鈥擡nergetics of Surfaces, Interfaces and WaterAdsorption鈥 (J. of the Amer. Ceramic Soc., 2011:3992鈥3999):

3.0鈭&濒迟;3.5 3.5鈭&濒迟;4.0 4.0鈭&濒迟;4.5 4.5鈭&濒迟;5.0 5.0鈭&濒迟;5.5

5 15 27 34 22

5.5鈭&濒迟;6.0 6.0鈭&濒迟;6.5 6.5鈭&濒迟;7.0 7.0鈭&濒迟;7.5 7.5鈭&濒迟;8.0

14 7 2 4 1

a. What proportion of the observations are less than 5?

b. What proportion of the observations are at least 6?

c. Construct a histogram with relative frequency on the vertical axis and comment on interesting features. In particular, does the distribution of particle sizes appear to be reasonably symmetric or somewhat skewed? (Note:The investigators fit lognormaldistribution to the data; this is discussed in Chapter 4.)

d. Construct a histogram with density on the vertical axis and compare to the histogram in (c).

Short Answer

Expert verified

a. The proportion of observations that are less than 5 is 0.618.

b. The proportion of observations that are at least 6 is 0.107

c. The histogram is represented as,

The shape of the distribution is not symmetric.

d. The histogram is represented as,

Step by step solution

01

Given information

Thedata on CeO2 particle sizes (nm) under certain experimental conditionsis provided as,

3.0鈭&濒迟;3.5

5

3.5鈭&濒迟;4.0

15

4.0鈭&濒迟;4.5

27

4.5鈭&濒迟;5.0

34

5.0鈭&濒迟;5.5

22

5.5鈭&濒迟;6.0

14

6.0鈭&濒迟;6.5

7

6.5鈭&濒迟;7.0

2

7.0鈭&濒迟;7.5

4

7.5鈭&濒迟;8.0

1

02

Compute the proportion

a.

The number of observations that are less than 5 is,

\(5 + 15 + 27 + 34 = 81\)

The total number of observations is 131.

The proportion of observations that are less than 5 is computed as,

\(\frac{{81}}{{131}} = 0.618\)

Thus, the proportion of observations that are less than 5 is approximately 0.618.

03

Compute the proportion

b.

The number of observations that are at least 6 is,

\(7 + 2 + 4 + 1 = 14\)

The total number of observations is 131.

The proportion of observations that are at least 6 is computed as,

\(\frac{{14}}{{131}} = 0.107\)

Thus, the proportion of observations that are at least 6 is approximately 0.107.

04

Construct a histogram with relative frequency on vertical axis

c.

The relative frequency is computed as,

\({\bf{relative frequency = }}\frac{{{\bf{frequency}}}}{{{\bf{Total}}\;{\bf{number}}\;{\bf{of}}\;{\bf{observations}}}}\)

The table representing the relative frequency is computed as,

class

frequency

relative frequency

3.0鈭&濒迟;3.5

5

0.038

3.5鈭&濒迟;4.0

15

0.115

4.0鈭&濒迟;4.5

27

0.206

4.5鈭&濒迟;5.0

34

0.260

5.0鈭&濒迟;5.5

22

0.168

5.5鈭&濒迟;6.0

14

0.107

6.0鈭&濒迟;6.5

7

0.053

6.5鈭&濒迟;7.0

2

0.015

7.0鈭&濒迟;7.5

4

0.031

7.5鈭&濒迟;8.0

1

0.008

Steps to construct a histogram are,

1) Determine the frequency or the relative frequency.

2) Mark the class boundaries on the horizontal axis.

3)Draw a rectangle on the horizontal axis corresponding to the frequency or relative frequency.

The histogram is represented as,

Observing the shape of the graph, it can be inferred that the graph is not exactly symmetric as it has an elongated tail in the right.

05

Construct a histogram with density on vertical axis

d.

The density value is computed as,

\({\bf{density = }}\frac{{{\bf{Relative}}\;{\bf{frequency}}}}{{{\bf{class}}\;{\bf{width}}}}\)

The table representing the densities is provided as,

class

frequency

relative frequency

density

3.0鈭&濒迟;3.5

5

0.038

0.076

3.5鈭&濒迟;4.0

15

0.115

0.229

4.0鈭&濒迟;4.5

27

0.206

0.412

4.5鈭&濒迟;5.0

34

0.260

0.519

5.0鈭&濒迟;5.5

22

0.168

0.336

5.5鈭&濒迟;6.0

14

0.107

0.214

6.0鈭&濒迟;6.5

7

0.053

0.107

6.5鈭&濒迟;7.0

2

0.015

0.031

7.0鈭&濒迟;7.5

4

0.031

0.061

7.5鈭&濒迟;8.0

1

0.008

0.015

Following the above steps, the histogram is represented as,

Comparing the above two histograms, there does not appear any change in both the diagrams.

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Most popular questions from this chapter

The three measures of center introduced in this chapter are the mean, median, and trimmed mean. Two additional measures of center that are occasionally used are the midrange,which is the average of the smallest and largest observations, and the midfourth,which is the average of the two fourths. Which of these five measures of center are resistant to the effects of outliers and which are not? Explain your reasoning.

Exposure to microbial products, especially endotoxin, may have an impact on vulnerability to allergic diseases. The article 鈥淒ust Sampling Methods for Endotoxin鈥擜n Essential, But Underestimated Issue鈥 (Indoor Air,2006: 20鈥27) considered various issues associated with determining endotoxin concentration. The following data on concentration (EU/mg) in settled dust for one sample of urban homes and another of farm homes was kindly supplied by the authors of the cited article.

U: 6.0 5.0 11.0 33.0 4.0 5.0 80.0 18.0 35.0 17.0 23.0

F: 4.0 14.0 11.0 9.0 9.0 8.0 4.0 20.0 5.0 8.9 21.0

9.2 3.0 2.0 0.3

  1. Determine the sample mean for each sample. How do they compare?
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A sample of 20 glass bottles of a particular type was selected, and the internal pressure strength of each bottle was determined. Consider the following partial sample information:
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Three smallest observations 125.8 188.1 193.7
Three largest observations 221.3 230.5 250.2


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A sample of n=10 automobiles was selected, and eachwas subjected to a 5-mph crash test. Denoting a car withno visible damage by S (for success) and a car with suchdamage by F, results were as follows:

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