We are told that the mean temperature for the first 4 days in January was -2°C. The mean temperature for the first 5 days in January was -3°C.
Now we will find sum of temperatures on first four days of January by multiplying 4 by -2.
[tex]\text{Sum of temperature on first 4 days}=4\cdot-2^{o}C[/tex]
[tex]\text{Sum of temperature on first 4 days}=-8^{o}C[/tex]
Now let us find sum of temperature on first 5 days of January.
[tex]\text{Sum of temperature on first 5 days}=5\cdot-3^{o}C[/tex]
[tex]\text{Sum of temperature on first 5 days}=-15^{o}C[/tex]
Now we will subtract -8 from -15 to find temperature on the 5th day of January.
[tex]\text{Temperature on 5th day of January}=-15-(-8)[/tex]
[tex]\text{Temperature on 5th day of January}=-15+8[/tex]
[tex]\text{Temperature on 5th day of January}=-7[/tex]
Therefore, temperature on the 5th day of January was [tex]-7^{o} C[/tex]
