Question

The mean temperature for the first 4 days in January was 1°C.

The mean temperature for the first 5 days in January was 3°C.
What was the temperature on the 5th day?

Answer 1

11°C because 1+1+1+1=4. 4/4=1.
So you do 3x5=15 which is how much the temperatures over the five days will add up to and then do 15-4 =11°