Chapter 21: Problem 3
A population consists of people of the following heights (in metres, numbers of individuals in brackets): \(1.80(1), 1.82(2), 1.84(4), 1.86(7), 1.88\) \((10), 1.90(15), 1.92(9), 1.94(4), 1.96(0), 1.98(1) .\) What are (a) the mean height, (b) the root mean square height of the population?
Short Answer
Expert verified
The mean height is obtained by dividing the weighted sum of heights by the total population, and the root mean square height is the square root of the average of the squares of the heights.
Step by step solution
01
Calculate the Mean Height
Multiply each height by the number of individuals with that height, sum these products, and then divide by the total population size. Use the formula for the mean: \[ \text{Mean Height} = \frac{\sum (\text{height} \times \text{number of individuals})}{\text{Total number of individuals}} \]
02
Compute the Products for Each Height
Calculate the products for each height: \(1.80 \times 1, 1.82 \times 2, 1.84 \times 4, \ldots, 1.98 \times 1\).
03
Sum the Products
Add up all the computed products from the previous step to get the numerator for the mean height calculation.
04
Count the Total Number of Individuals
Add the number of individuals at each height to determine the total population size.
05
Divide to Obtain the Mean
Divide the sum of the products by the total population size from step 4 to calculate the mean height.
06
Calculate the Root Mean Square Height
Square each height, multiply by the number of individuals, sum these squared products, divide by the total number of individuals, and then take the square root. Use the formula: \[ \text{Root Mean Square Height} = \sqrt{\frac{\sum(\text{height}^2 \times \text{number of individuals})}{\text{Total number of individuals}}} \]
07
Compute Squared Products for Each Height
For each height, square it and then multiply by the corresponding number of individuals.
08
Sum the Squared Products
Add all the squared products calculated in the previous step to get the numerator for the root mean square height.
09
Divide to Obtain the Root Mean Square
Divide the sum of the squared products by the total number of individuals and take the square root to get the root mean square height.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Mean Height Calculation
Understanding the mean height of a population is crucial for comprehending statistical distribution. This value, commonly known as the average, is found by adding up all individual heights and dividing by the total number of individuals in the population. It gives us an insight into the central tendency of height within a group.
For example, to calculate the mean height given a series of heights and corresponding frequencies, each height is multiplied by its frequency. These products are summed up to get a numerator, which is then divided by the total population size. Mathematically, the mean height is represented as:
\[\begin{equation} Mean Height = \frac{\sum (height \times number of individuals)}{Total number of individuals}\end{equation}\]
Remember, the mean is sensitive to outliers in a data set; very high or very low values can skew the mean. Therefore, it's beneficial to look at this measure in conjunction with other statistical parameters to get a comprehensive understanding of the data.
For example, to calculate the mean height given a series of heights and corresponding frequencies, each height is multiplied by its frequency. These products are summed up to get a numerator, which is then divided by the total population size. Mathematically, the mean height is represented as:
\[\begin{equation} Mean Height = \frac{\sum (height \times number of individuals)}{Total number of individuals}\end{equation}\]
Remember, the mean is sensitive to outliers in a data set; very high or very low values can skew the mean. Therefore, it's beneficial to look at this measure in conjunction with other statistical parameters to get a comprehensive understanding of the data.
Root Mean Square Height
While the mean height provides a good measure of central tendency, the root mean square (RMS) height offers a slightly different perspective. This calculation gives more weight to extreme values, as it involves squaring each height before averaging.
The RMS height is especially useful in physical applications where the square of the value is more meaningful, such as in quantum mechanics or signal processing. To compute it, we square each height, multiply by the frequency, sum all these squared heights, and then divide by the total population. The square root of this result gives us the RMS height:
\[\begin{equation} Root Mean Square Height = \sqrt{\frac{\sum(height^2 \times number of individuals)}{Total number of individuals}}\end{equation}\]
The RMS height often results in a higher value than the mean height when the distribution of values is wide because squaring the heights emphasizes larger values more.
The RMS height is especially useful in physical applications where the square of the value is more meaningful, such as in quantum mechanics or signal processing. To compute it, we square each height, multiply by the frequency, sum all these squared heights, and then divide by the total population. The square root of this result gives us the RMS height:
\[\begin{equation} Root Mean Square Height = \sqrt{\frac{\sum(height^2 \times number of individuals)}{Total number of individuals}}\end{equation}\]
The RMS height often results in a higher value than the mean height when the distribution of values is wide because squaring the heights emphasizes larger values more.
Population Statistics
In the realm of physical chemistry and beyond, population statistics provide a mathematical framework to describe a set of measurements or observations. This set, or 'population', can include values like the heights of individuals or temperatures during a chemical reaction.
Key statistical measures derived from a population include the mean and root mean square, as well as variance and standard deviation. These measures capture the central tendency and the spread or variability of data.
- The Mean reflects the average value.
- The Root Mean Square offers a measure that is sensitive to outliers.
- The Variance indicates how data points are spread around the mean.
- The Standard Deviation provides a way to gauge the amount of variation or dispersion in a set of values.
Understanding these statistics is essential for chemists to reliably interpret experimental data and validate theoretical models.
Key statistical measures derived from a population include the mean and root mean square, as well as variance and standard deviation. These measures capture the central tendency and the spread or variability of data.
- The Mean reflects the average value.
- The Root Mean Square offers a measure that is sensitive to outliers.
- The Variance indicates how data points are spread around the mean.
- The Standard Deviation provides a way to gauge the amount of variation or dispersion in a set of values.
Understanding these statistics is essential for chemists to reliably interpret experimental data and validate theoretical models.
Data Analysis in Chemistry
Data analysis in chemistry involves methodically scrutinizing data obtained from experiments and observations to decide upon the validity and reliability of the results. Statistical tools are employed to articulate the significance of data, which can impact further experiments or theoretical advancements.
Chemists deal with data that contains natural variability. To make sense of it, they use statistical parameters to quantify and describe this variability. Techniques such as regression analysis to find trends, hypothesis testing to make decisions based on data, and exploratory data analysis to find patterns, are all parts of a chemist's data analysis toolkit.
The capacity to deftly analyze data empowers chemists to discern subtle patterns, draw informed conclusions, and design better experiments or products. Therefore, proficiency in statistics and data analysis is as crucial in chemistry as understanding the very reactions and compounds with which chemists work.
Chemists deal with data that contains natural variability. To make sense of it, they use statistical parameters to quantify and describe this variability. Techniques such as regression analysis to find trends, hypothesis testing to make decisions based on data, and exploratory data analysis to find patterns, are all parts of a chemist's data analysis toolkit.
The capacity to deftly analyze data empowers chemists to discern subtle patterns, draw informed conclusions, and design better experiments or products. Therefore, proficiency in statistics and data analysis is as crucial in chemistry as understanding the very reactions and compounds with which chemists work.