Question

Difficulty: MediumInterpreting Linear Relationships in Context

A researcher uses the linear equation T=18.5+4.2dT = 18.5 + 4.2d to estimate the temperature, TT, in degrees Celsius, of the Earth's crust at a depth of dd kilometers below the surface in a certain region. What is the estimated increase in temperature, in degrees Celsius, for each increase of 5 kilometers in depth?

Answer: 21 degrees Celsius

Answer

21
The coefficient of dd in the equation is 4.24.2, representing a temperature increase of 4.24.2 degrees Celsius for every 1 kilometer increase in depth. To find the temperature increase for an increase of 5 kilometers in depth, multiply this rate of change by 5: 4.2×5=214.2 \times 5 = 21.

Step-by-Step Solution

1
Identify the slope of the linear equation.
The slope is 4.24.2.
In the equation T=18.5+4.2dT = 18.5 + 4.2d, the term 4.2d4.2d indicates that for every 1 kilometer increase in depth (dd), the temperature (TT) increases by 4.24.2 degrees Celsius.
2
Calculate the total temperature increase for a 5-kilometer depth increase.
The increase is 2121 degrees Celsius.
Since the rate of temperature increase is 4.24.2 degrees Celsius per kilometer, a depth increase of 55 kilometers results in a temperature increase of 4.2×5=214.2 \times 5 = 21 degrees Celsius.

Key Concept

Interpreting the slope of a linear equation in context as a constant rate of change.
Estimated Time:1m 30s
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