Question

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. What was the temperature on the 5th day?

Answer 1

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.

`\text{Sum of temperature on first 4 days}=4\cdot-2^(o)C`

`\text{Sum of temperature on first 4 days}=-8^(o)C`

Now let us find sum of temperature on first 5 days of January.

`\text{Sum of temperature on first 5 days}=5\cdot-3^(o)C`

`\text{Sum of temperature on first 5 days}=-15^(o)C`

Now we will subtract -8 from -15 to find temperature on the 5th day of January.

`\text{Temperature on 5th day of January}=-15-(-8)`

`\text{Temperature on 5th day of January}=-15+8`

`\text{Temperature on 5th day of January}=-7`

Therefore, temperature on the 5th day of January was
`-7^(o) C`