Art of Problem Solving

2022 AMC 8 Problems/Problem 9: Difference between revisions

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A cup of boiling water (<math>212^{\circ}\text{F}</math>) is placed to cool in a room whose temperature remains constant at <math>68^{\circ}\text{F}</math>. Suppose the difference between the water temperature and the room temperature is halved every <math>5</math> minutes. What is the water temperature, in degrees Fahrenheit, after <math>15</math> minutes?
A cup of boiling water (<math>212^{\circ}\text{F}</math>) is placed to cool in a room whose temperature remains constant at <math>68^{\circ}\text{F}</math>. Suppose the difference between the water temperature and the room temperature is halved every <math>5</math> minutes. What is the water temperature, in degrees Fahrenheit, after <math>15</math> minutes?
   
   
<math>\textbf{(A)} ~77\qquad\textbf{(B)} ~86\qquad\textbf{(C)} ~92\qquad\textbf{(D)} ~98\qquad\textbf{(E)} ~104</math>
<math>\textbf{(A) } 77 \qquad \textbf{(B) } 86 \qquad \textbf{(C) } 92 \qquad \textbf{(D) } 98 \qquad \textbf{(E) } 104</math>


==Solution==
==Solution==

Revision as of 11:07, 28 January 2022

Problem

A cup of boiling water ($212^{\circ}\text{F}$) is placed to cool in a room whose temperature remains constant at $68^{\circ}\text{F}$. Suppose the difference between the water temperature and the room temperature is halved every $5$ minutes. What is the water temperature, in degrees Fahrenheit, after $15$ minutes?

$\textbf{(A) } 77 \qquad \textbf{(B) } 86 \qquad \textbf{(C) } 92 \qquad \textbf{(D) } 98 \qquad \textbf{(E) } 104$

Solution

See Also

2022 AMC 8 (ProblemsAnswer KeyResources)
Preceded by
Problem 8
Followed by
Problem 10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AJHSME/AMC 8 Problems and Solutions

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