Question

The temperature outside is currently 10°F. It will fall at a constant rate of 3°F per hour. Which temperature will it be in 4 hours?

A
22°F
B
7°F
С
-2°F
D
-12°F

Answer 1

The temperature in 4 hours = -2 °F

Thus, option (D) is true.

Explanation:

We know that the slope-intercept form of the line equation is

`y = mx+b`

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

`y = mx+b`

`y = -3x + 10`

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.