Math Problem Statement

The accompanying table shows the number of bacteria present in a certain culture over a 5 hour period, where x is the time, in hours, and y is the number of bacteria. Write an exponential regression equation for this set of data, rounding all coefficients to the nearest hundredth. Using this equation, determine the number of bacteria present after 16 hours, to the nearest whole number. Hours (x) Bacteria (y) 00 8989 11 9999 22 108108 33 122122 44 132132 55 139139

Solution

To find an exponential regression equation for the given data and determine the number of bacteria after 16 hours, we'll follow these steps:


Step 1: Exponential Regression Equation

The general form of an exponential equation is:
y=abxy = a \cdot b^x
where:

  • yy is the dependent variable (bacteria count),
  • xx is the independent variable (time in hours),
  • aa is the initial value (bacteria at x=0x = 0),
  • bb is the growth factor per hour.

We'll use the given data to compute the values of aa and bb.


Step 2: Use the Data for Exponential Regression

The data:

x &: 0, 1, 2, 3, 4, 5 \\ y &: 8989, 9999, 108108, 122122, 132132, 139139 \\ \end{aligned}$$ Using these values, an exponential regression equation can be calculated. I'll do this step now. numpy as np from scipy.optimize import curve_fit # Given data x = np.array([0, 1, 2, 3, 4, 5]) # Time in hours y = np.array([8989, 9999, 108108, 122122, 132132, 139139]) # Bacteria count # Exponential function definition def exp_func(x, a, b): return a * b**x # Fit the data to the exponential function params, _ = curve_fit(exp_func, x, y) # Extract the coefficients a and b a, b = params # Predict the number of bacteria after 16 hours x_predict = 16 y_predict = exp_func(x_predict, a, b) a_rounded, b_rounded, y_predict_rounded = round(a, 2), round(b, 2), round(y_predict) a_rounded, b_rounded, y_predict_rounded### **Exponential Regression Equation** The exponential regression equation for the given data is: $$y = 39659.98 \cdot 1.32^x$$ --- ### **Step 3: Predict the Number of Bacteria After 16 Hours** Using the regression equation $$y = 39659.98 \cdot 1.32^x$$, substituting $$x = 16$$, we get: $$y = 39659.98 \cdot 1.32^{16} \approx 3,454,301$$ Thus, the number of bacteria present after 16 hours is approximately: $$\boxed{3,454,301}$$ --- ### Would you like a detailed breakdown or clarification? Here are **5 follow-up questions** to expand your understanding: 1. How is the growth factor $$b$$ derived in an exponential regression? 2. What does the initial value $$a$$ represent in this context? 3. How does this model differ from a linear regression for the same data? 4. Can this equation be used for very large $$x$$ values? Why or why not? 5. What would happen if the bacteria grew at a linear rate instead of exponentially? --- **Tip**: When working with exponential growth, always check if the model fits the data well before making long-term predictions.

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Math Problem Analysis

Mathematical Concepts

Exponential Growth
Regression Analysis
Predictive Modeling

Formulas

Exponential growth formula y = a * b^x
Curve fitting techniques for exponential regression

Theorems

Least Squares Method for Regression Analysis

Suitable Grade Level

Grades 10-12