Answer : The 5th day = 3 Celsius
Explanation:
the average of the first 4 day is 8
Which mean the combine temp on the first 4 day is 8 x 4 = 32
Now on the first 5 day the average temp is 7
Then the combine temp on the first 5 day is 7 x 5 = 35
Find the 5th day
4 days combine temp + 5th day = the combine temp of 5 days
32 + 5th day = 35
5th day = 35-32
5th day temp = 3C