To find the temperature change per hour, we calculate the total change in temperature and divide it by the time taken (4 hours).

The total temperature change: $7.5^\circ C - (-5.3^\circ C) = 7.5^\circ C + 5.3^\circ C = 12.8^\circ C$

Now, to find the rate of change per hour, divide the total temperature change by 4 hours: $\frac{12.8^\circ C}{4 \, \text{hours}} = 3.2^\circ C \, \text{per hour}$

So, the temperature changed by 3.2°C per hour.

Would you like more details or have any questions?

Here are some related questions:

1. What is the formula to calculate average temperature change?
2. How does the concept of rate apply in temperature change problems?
3. Can temperature change rates be negative? What does that signify?
4. If the temperature changed over 8 hours instead of 4, how would the rate per hour differ?
5. How would you calculate the total temperature change if the rate per hour is known?

Tip: Always keep track of units when performing calculations to avoid errors.