Calculating the Initial Value and Decay Rate

Oct 13, 2025 by wbrum.org 1 views

Introduction

When it comes to the temperature of a cup of coffee, it's not just about the initial temperature, but also about how it changes over time. In this article, we will delve into the world of mathematics and explore the temperature of a cup of coffee using a real-world example. We will analyze the data provided in the table below and use mathematical concepts to understand the temperature of the coffee over time.

The Data

Minute	Temperature ( $^{\circ} F$ )
0	192
5	184
10	176
15	168
20	160
25	152
30	144
35	136
40	128
45	120
50	112
55	104
60	96

The Problem

The problem at hand is to analyze the temperature of the coffee over time and determine the rate at which it is cooling. We can use mathematical concepts such as linear regression and exponential decay to understand the temperature of the coffee.

Linear Regression

One way to analyze the temperature of the coffee is to use linear regression. Linear regression is a statistical method that models the relationship between a dependent variable (in this case, the temperature of the coffee) and one or more independent variables (in this case, time). The equation for linear regression is:

y = mx + b

where y is the dependent variable, x is the independent variable, m is the slope of the line, and b is the y-intercept.

To apply linear regression to the data, we need to calculate the slope and y-intercept of the line. We can do this by using the following formulas:

m = (n * Σxy - Σx * Σy) / (n * Σx^2 - (Σx)^2)

b = (Σy - m * Σx) / n

where n is the number of data points, Σxy is the sum of the products of the x and y values, Σx is the sum of the x values, Σy is the sum of the y values, and Σx^2 is the sum of the squares of the x values.

Calculating the Slope and Y-Intercept

Using the formulas above, we can calculate the slope and y-intercept of the line. First, we need to calculate the sum of the products of the x and y values, the sum of the x values, the sum of the y values, and the sum of the squares of the x values.

Minute	Temperature ( $^{\circ} F$ )	x	y	xy	x^2
0	192	0	192	0	0
5	184	5	184	920	25
10	176	10	176	1760	100
15	168	15	168	2520	225
20	160	20	160	3200	400
25	152	25	152	3800	625
30	144	30	144	4320	900
35	136	35	136	4760	1225
40	128	40	128	5120	1600
45	120	45	120	5400	2025
50	112	50	112	5600	2500
55	104	55	104	5720	3025
60	96	60	96	5760	3600

Now, we can calculate the sum of the products of the x and y values, the sum of the x values, the sum of the y values, and the sum of the squares of the x values.

Σxy = 5760 Σx = 360 Σy = 1920 Σx^2 = 18125

Now, we can calculate the slope and y-intercept of the line.

m = (12 * 5760 - 360 * 1920) / (12 * 18125 - 360^2) m = -1.6

b = (1920 - (-1.6) * 360) / 12 b = 160

The Equation of the Line

Now that we have the slope and y-intercept of the line, we can write the equation of the line.

y = -1.6x + 160

Exponential Decay

Another way to analyze the temperature of the coffee is to use exponential decay. Exponential decay is a mathematical concept that models the decrease in a quantity over time. The equation for exponential decay is:

y = a * e^(-kt)

where y is the dependent variable, a is the initial value, e is the base of the natural logarithm, k is the decay rate, and t is time.

To apply exponential decay to the data, we need to calculate the initial value and the decay rate. We can do this by using the following formulas:

a = y0 k = -ln(a) / t

where y0 is the initial value, and t is time.

Calculating the Initial Value and Decay Rate

Using the formulas above, we can calculate the initial value and decay rate of the line. First, we need to calculate the initial value.

a = 192

Now, we can calculate the decay rate.

k = -ln(192) / 60 k = 0.012

The Equation of the Exponential Decay

Now that we have the initial value and decay rate of the line, we can write the equation of the exponential decay.

y = 192 * e^(-0.012t)

Conclusion

In this article, we analyzed the temperature of a cup of coffee using linear regression and exponential decay. We calculated the slope and y-intercept of the line using linear regression, and we calculated the initial value and decay rate of the line using exponential decay. We then wrote the equation of the line for both linear regression and exponential decay. The results show that the temperature of the coffee decreases over time, with a rate of -1.6 degrees per minute for linear regression and a rate of 0.012 per minute for exponential decay.

Introduction

In our previous article, we analyzed the temperature of a cup of coffee using linear regression and exponential decay. We calculated the slope and y-intercept of the line using linear regression, and we calculated the initial value and decay rate of the line using exponential decay. We then wrote the equation of the line for both linear regression and exponential decay. In this article, we will answer some of the most frequently asked questions about the temperature of a cup of coffee.

Q: What is the initial temperature of the coffee?

A: The initial temperature of the coffee is 192 degrees Fahrenheit.

Q: How does the temperature of the coffee change over time?

A: The temperature of the coffee decreases over time. Using linear regression, we calculated a rate of -1.6 degrees per minute, and using exponential decay, we calculated a rate of 0.012 per minute.

Q: What is the equation of the line for linear regression?

A: The equation of the line for linear regression is y = -1.6x + 160.

Q: What is the equation of the line for exponential decay?

A: The equation of the line for exponential decay is y = 192 * e^(-0.012t).

Q: How long does it take for the coffee to cool down to 100 degrees Fahrenheit?

A: To find the time it takes for the coffee to cool down to 100 degrees Fahrenheit, we can use the equation of the line for linear regression. We can set y = 100 and solve for x.

100 = -1.6x + 160

x = 25 minutes

Q: How long does it take for the coffee to cool down to 50 degrees Fahrenheit?

A: To find the time it takes for the coffee to cool down to 50 degrees Fahrenheit, we can use the equation of the line for linear regression. We can set y = 50 and solve for x.

50 = -1.6x + 160

x = 50 minutes

Q: Can I use the equation of the line for exponential decay to find the time it takes for the coffee to cool down to 100 degrees Fahrenheit?

A: Yes, you can use the equation of the line for exponential decay to find the time it takes for the coffee to cool down to 100 degrees Fahrenheit. We can set y = 100 and solve for t.

100 = 192 * e^(-0.012t)

t = 60 minutes

Q: Can I use the equation of the line for exponential decay to find the time it takes for the coffee to cool down to 50 degrees Fahrenheit?

A: Yes, you can use the equation of the line for exponential decay to find the time it takes for the coffee to cool down to 50 degrees Fahrenheit. We can set y = 50 and solve for t.

50 = 192 * e^(-0.012t)

t = 120 minutes

Conclusion

In this article, we answered some of the most frequently asked questions about the temperature of a cup of coffee. We used linear regression and exponential decay to analyze the temperature of the coffee and calculated the slope and y-intercept of the line using linear regression, and we calculated the initial value and decay rate of the line using exponential decay. We then wrote the equation of the line for both linear regression and exponential decay. The results show that the temperature of the coffee decreases over time, with a rate of -1.6 degrees per minute for linear regression and a rate of 0.012 per minute for exponential decay.

Minute	Temperature ( $^{\circ} F$ )
0	192
5	184
10	176
15	168
20	160
25	152
30	144
35	136
40	128
45	120
50	112
55	104
60	96

Minute	Temperature ( $^{\circ} F$ )
0	192
5	184
10	176
15	168
20	160
25	152
30	144
35	136
40	128
45	120
50	112
55	104
60	96

Minute	Temperature ( $^{\circ} F$ )
0	192
5	184
10	176
15	168
20	160
25	152
30	144
35	136
40	128
45	120
50	112
55	104
60	96