The mean temperature for the first 7 days in January was 4 °C.

The temperature on the 8th day was 4 °C.

What is the mean temperature for the first 8 days in January?

4 degrees Celsius

Step-by-step explanation:

Since the mean is (total/amount), we can remake this to get That mean*amount=total. For the first 7 days, 4*7=28 for our total, and add that to the 8th day to get 32 for our total. 32/8=4 for our mean for the first 8 days of january