Math Problem Statement

Exponential Regression Use exponential regression to fit the following data set. x 1 2 3 4 5 y 53.0 55.2 57.4 59.7 62.0 accurate answers, show working, and break it down

Solution

To perform exponential regression on the dataset, we need to find an exponential model in the form:

y=ae(bx)y = a \cdot e^{(b \cdot x)}

where:

  • yy is the output (dependent variable),
  • xx is the input (independent variable),
  • aa and bb are constants to be determined.

The given data points are:

x:1,2,3,4,5x: 1, 2, 3, 4, 5 y:53.0,55.2,57.4,59.7,62.0y: 53.0, 55.2, 57.4, 59.7, 62.0

Step 1: Transform the Exponential Equation to a Linear Form

Since the exponential function y=ae(bx)y = a \cdot e^{(b \cdot x)} is not linear, we can take the natural logarithm of both sides to linearize it:

ln(y)=ln(ae(bx))=ln(a)+bx\ln(y) = \ln(a \cdot e^{(b \cdot x)}) = \ln(a) + b \cdot x

Let:

  • Y=ln(y)Y = \ln(y) (transformed dependent variable),
  • A=ln(a)A = \ln(a),
  • bb remains the slope.

This transformation gives a linear equation: Y=A+bxY = A + b \cdot x

Now we can use linear regression to find the values of AA and bb, and then determine a=eAa = e^A.

Step 2: Transform the Data

Let's calculate ln(y)\ln(y) for each yy value.

y:53.0,55.2,57.4,59.7,62.0y: 53.0, 55.2, 57.4, 59.7, 62.0 ln(y):ln(53.0),ln(55.2),ln(57.4),ln(59.7),ln(62.0)\ln(y): \ln(53.0), \ln(55.2), \ln(57.4), \ln(59.7), \ln(62.0)

Computing each:

ln(53.0)3.9703\ln(53.0) \approx 3.9703 ln(55.2)4.0100\ln(55.2) \approx 4.0100 ln(57.4)4.0492\ln(57.4) \approx 4.0492 ln(59.7)4.0884\ln(59.7) \approx 4.0884 ln(62.0)4.1271\ln(62.0) \approx 4.1271

Thus, we have the transformed data set:

x:1,2,3,4,5x: 1, 2, 3, 4, 5 Y:3.9703,4.0100,4.0492,4.0884,4.1271Y: 3.9703, 4.0100, 4.0492, 4.0884, 4.1271

Step 3: Calculate bb and AA Using Linear Regression Formulas

To find bb (slope) and AA (intercept), we use the formulas:

b=n(xY)xYn(x2)(x)2b = \frac{n \sum(xY) - \sum x \sum Y}{n \sum(x^2) - (\sum x)^2} A=YbxnA = \frac{\sum Y - b \sum x}{n}

where n=5n = 5 (the number of data points).

Let's calculate each component:

  1. Sum of xx: x=1+2+3+4+5=15\sum x = 1 + 2 + 3 + 4 + 5 = 15

  2. Sum of YY: Y=3.9703+4.0100+4.0492+4.0884+4.1271=20.245\sum Y = 3.9703 + 4.0100 + 4.0492 + 4.0884 + 4.1271 = 20.245

  3. Sum of x2x^2: (x2)=12+22+32+42+52=55\sum(x^2) = 1^2 + 2^2 + 3^2 + 4^2 + 5^2 = 55

  4. Sum of xYx \cdot Y: (xY)=(13.9703)+(24.0100)+(34.0492)+(44.0884)+(54.1271)=84.92\sum(xY) = (1 \cdot 3.9703) + (2 \cdot 4.0100) + (3 \cdot 4.0492) + (4 \cdot 4.0884) + (5 \cdot 4.1271) = 84.92

Now we can plug these values into the formulas.

Calculating bb:

b=584.921520.245555152b = \frac{5 \cdot 84.92 - 15 \cdot 20.245}{5 \cdot 55 - 15^2} b=424.6303.675275225=120.92550=2.4185b = \frac{424.6 - 303.675}{275 - 225} = \frac{120.925}{50} = 2.4185

Calculating AA:

A=20.245(2.418515)5A = \frac{20.245 - (2.4185 \cdot 15)}{5} A=20.24536.27755=16.03255=3.2065A = \frac{20.245 - 36.2775}{5} = \frac{-16.0325}{5} = -3.2065

Step 4: Determine aa

Since A=ln(a)A = \ln(a), we have: a=e3.20650.0406a = e^{-3.2065} \approx 0.0406

Step 5: Write the Exponential Model

With a0.0406a \approx 0.0406 and b2.4185b \approx 2.4185, our exponential model is:

y=0.0406e(2.4185x)y = 0.0406 \cdot e^{(2.4185 \cdot x)}

This model represents the best exponential fit for the given data.

Would you like further clarification on any of the steps?

Here are five questions related to exponential regression and this model:

  1. How does changing the base of the exponential function affect the model?
  2. Why is taking the natural logarithm useful for exponential regression?
  3. How would you interpret the constant bb in this context?
  4. Can exponential regression be applied to data that decreases over time?
  5. What are some real-world applications of exponential regression?

Tip: Remember, exponential regression is particularly useful for data that grows (or decays) at an increasing rate, such as population growth or radioactive decay.

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Math Problem Analysis

Mathematical Concepts

Exponential Regression
Natural Logarithms
Linear Regression
Data Transformation

Formulas

y = a * e^(b * x)
ln(y) = ln(a) + b * x (transformation)
Linear regression formulas for slope (b) and intercept (A)
a = e^A

Theorems

Linear Regression Transformation for Exponential Functions

Suitable Grade Level

Grades 10-12