2023 AMC 10A Problems/Problem 8

Problem

Barb the baker has developed a new temperature scale for her bakery called the Breadus scale, which is a linear function of the Fahrenheit scale. Bread rises at $110$ degrees Fahrenheit, which is $0$ degrees on the Breadus scale. Bread is baked at $350$ degrees Fahrenheit, which is $100$ degrees on the Breadus scale. Bread is done when its internal temperature is $200$ degrees Fahrenheit. What is this in degrees on the Breadus scale?

$\textbf{(A) }33\qquad\textbf{(B) }34.5\qquad\textbf{(C) }36\qquad\textbf{(D) }37.5\qquad\textbf{(E) }39$

Solution 1

To solve this question, you can use $y = mx + b$ where the $x$ is the Fahrenheit and the $y$ is the Breadus. We have $(110,0)$ and $(350,100)$ . We want to find $(200,y)$ . The slope for these two points is $\frac{5}{12}$ ; $y = \frac{5}{12}x + b$ . Solving for $b$ using $(110, 0)$ , $\frac{550}{12} = -b$ . We get $b = \frac{-275}{6}$ . Plugging in $(200, y), \frac{1000}{12}-\frac{550}{12}=y$ . Simplifying, $\frac{450}{12} = \boxed{\textbf{(D) }37.5}$

~walmartbrian

Solution 2 (faster)

Let $^\circ B$ denote degrees Breadus. We notice that $200^\circ F$ is $90^\circ F$ degrees to $0^\circ B$ , and $150^\circ F$ to $100^\circ B$ . This ratio is $90:150=3:5$ ; therefore, $200^\circ F$ will be $\dfrac3{3+5}=\dfrac38$ of the way from $0$ to $100$ , which is $\boxed{\textbf{(D) }37.5.}$

~Technodoggo

2023 AMC 10A (Problems • Answer Key • Resources)
Preceded by Problem 7	Followed by Problem 9
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2023 AMC 10A Problems/Problem 8

Contents

Problem

Solution 1

Solution 2 (faster)

See Also