Chapter 4: Problem 10
The following data represent the length and weight of a set of fish (bass). Model weight as a function of the length of the fish. \begin{tabular}{l|llllll} Length (in.) & \(12.5\) & \(12.625\) & \(14.125\) & \(14.5\) & \(17.25\) & \(17.75\) \\ \hline Weight (oz) & 17 & \(16.5\) & 23 & \(26.5\) & 41 & 49 \end{tabular}
Short Answer
Step by step solution
Understand the Problem
Choose a Model Type
Set Up Equations for Linear Regression
Calculate Required Sums
Calculate Slope \(m\) and Intercept \(b\)
Write the Regression Equation
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Mathematical Modeling
At its core, modeling involves choosing a type of equation, such as a linear equation, to describe the situation. This provides a way to quantify relationships in a way that can be analyzed mathematically. By using a mathematical model, we can gain insights into the relationship between variables—in this case, how a fish's length might affect its weight.
The linear model expressed as \( W = mL + b \) serves as a prediction tool, where \( W \) is the dependent variable (weight), \( L \) is the independent variable (length), \( m \) is the slope, and \( b \) is the intercept.
Data Analysis
Here, we specifically perform a type of analysis known as linear regression. This method is used to understand and predict the relationship between two quantitative variables.
Key steps in our data analysis involve:
- Calculating sums of the data points, such as total lengths \( \sum{x} \), weights \( \sum{y} \), cross-products of length and weight \( \sum{xy} \), and squares of lengths \( \sum{x^2} \).
- Using these sums to determine the linear regression line by calculating the slope \( m \) and y-intercept \( b \).
- Applying the formulas so we can predict the fish weight based on length.
Linear Functions
In this exercise, we're using a linear function \( W = 3.98L - 28.8 \) to represent the relationship between the length \( L \) and the weight \( W \) of the fish.
Linear functions have several important properties:
- The slope \( m \) indicates how much \( y \) (or weight, in our case) changes for a one-unit increase in \( x \) (or length). Here, the slope 3.98 suggests that for each inch increase in length, the fish's weight increases by approximately 3.98 oz.
- The y-intercept \( b \) tells us the value of \( y \) when \( x \) is zero. Although it might not have a practical interpretation in this context, it is still a necessary component of the function.
- Linear functions provide a straightforward method for predicting values within or close to the range of given data points.