3.1.5 AP Calculus Exam average temperature

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Discussion Overview

The discussion revolves around a problem from an AP Calculus exam concerning the average temperature of water in a tub over a specified time period. Participants explore how to estimate the derivative of the temperature function at a given time and discuss the implications of using the average value of the function over the interval.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • Post 1 presents a table of temperature values at specific times and asks for an estimate of W'(12) using the provided data.
  • Post 1 also questions whether the approximation for the average temperature is optimistic or pessimistic, indicating uncertainty about the implications of the average value calculation.
  • Post 2 suggests a method for estimating W'(12) using the difference quotient between W(15) and W(9), while also questioning the completeness of the citation of the problem in part (b).
  • Post 3 confirms the citation of the problem and proposes that the average temperature might be calculated by averaging the first and last points, but expresses uncertainty about the correctness of this approach.
  • Post 4 provides a link to an external resource, possibly for further clarification or reference regarding the problem.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best approach to estimate W'(12) or the implications of the average temperature calculation. There are differing interpretations of how to approach the problem and uncertainty about the correctness of proposed methods.

Contextual Notes

Participants express uncertainty regarding the completeness of the problem citation and the implications of the average temperature calculation. There is also a lack of clarity on whether the average temperature approximation is optimistic or pessimistic.

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309 average temperature
$$\begin{array}{|c|c|c|c|c|c|c|}
\hline
t\,(minutes)&0&4&9&15&20\\
\hline
W(t)\,(degrees Farrenheit)&55.0&57.1&61.8&67.9&71.0\\
\hline
\end{array}$$
The temperature of water in a tub at time t is modeled by a strictly increasing, twice-differentiable function W. where W(t) is measured in degrees Fahrenheit and t is measured in minutes.
At time $t=0$. the temperature of the water is $55^o F$.
The water is heated for 30 minutes, beginning at time $t=0$,
Values of $W(t)$ at selected times t for the first 20 minutes are given in the table above.

a. Use the data in the table to estimate W'(12).
b. Show the computations that lead to your answer. using correct units,
c. For $0\le t \le 20$ the average temperature of the water in the tub is
$\dfrac{1}{20}\int_0^{20} W(t)\, dt$
Does this approximation overoptimistic or underestimate the average temperature of the water over these 20 minutes? Explain.

ok not sure just what kind of equation we need for this since the points are close to a straight line

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Re: 309 AP Dalculus Exam average temperature

(a) $W'(12) \approx \dfrac{W(15)-W(9)}{15-9} \, \dfrac{^oF}{min}$

(b) ... is this part a complete citation of the given question? Does part (c) depend on a complete citation of the question in part (b) ?
 
Re: 309 AP Dalculus Exam average temperature

that was exactly the way it was given
so I presume first they just want average between the first and last point

then they want a addition of the sums of the intervals which would be close.

don't actually know their answer...
 

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