A scientist puts a substance in a freezer, where the temperature of the substance changes by -1/9 º C per minute. At 8:00 PM, the temperature of the substance was –9ºC. Find the temperature of this substance at each
time below and write a multiplication expression to represent the change in temperature.
To find the temperature of the substance at each time, we need to determine the amount of time that has passed since 8:00 PM and the corresponding change in temperature.
Let's denote x as the number of minutes that have passed since 8:00 PM.
Since the temperature changes by -1/9 ºC per minute, the change in temperature after x minutes can be represented by the multiplication expression -1/9 * x ºC.
To find the temperature of the substance at each time, we need to add the change in temperature to the initial temperature of -9ºC.
1) At 8:05 PM (5 minutes have passed since 8:00 PM):
The change in temperature after 5 minutes is -1/9 * 5 = -5/9 ºC.
The temperature of the substance would be -9ºC + (-5/9 ºC) = -14/9 ºC.
2) At 8:10 PM (10 minutes have passed since 8:00 PM):
The change in temperature after 10 minutes is -1/9 * 10 = -10/9 ºC.
The temperature of the substance would be -9ºC + (-10/9 ºC) = -99/9 ºC.
3) At 8:15 PM (15 minutes have passed since 8:00 PM):
The change in temperature after 15 minutes is -1/9 * 15 = -15/9 = -5/3 ºC.
The temperature of the substance would be -9ºC + (-5/3 ºC) = -32/3 ºC.
The multiplication expression that represents the change in temperature is -1/9 * x ºC, where x represents the number of minutes that have passed since 8:00 PM.