Answer:
The temperature in 4 hours = -2 °F
Thus, option (D) is true.
Step-by-step explanation:
We know that the slope-intercept form of the line equation is

where m is the rate of change or slope and b is the y-intercept
- Let 'y' be the temperature
- Let 'x' be the time of the temperature in the hour
Given that the current temperature outside = 10°F.
Thus, the y-intercept = b = 10°F
Given that as the day went on, It will fall at a constant rate of 3°F per hour.
Thus, the slope or rate of change = -3°F
(The rate of change or slope is -3 because the temperature is reducing)
Thus, the rate of change = slope = m = -3
Thus, substituting m = -3 and b = 10 in the equation


Now, substituting x = 4 to determine the temperature after 4 hours.
y = -3(4) + 10
y = -12 + 12
y = -2 °F
Therefore, the temperature in 4 hours = -2 °F
Thus, option (D) is true.