In a science experiment, the temperature of a substance is changed from 42 degrees Fahrenheit to -54 degrees Fahrenheit at an average rate of -12 degrees per hour. Over how many hours does the change take place?

8 hrs

(42 + 54) / 12 = ________ hours

Right!

To find the number of hours it takes for the temperature change to occur, we can use the formula:

Number of hours = (Final temperature - Initial temperature) / Average rate of change

Given:
Initial temperature = 42 degrees Fahrenheit
Final temperature = -54 degrees Fahrenheit
Average rate of change = -12 degrees per hour

Substituting these values into the formula, we get:

Number of hours = (-54 - 42) / -12
= -96 / -12
= 8

Therefore, the temperature change takes place over 8 hours.