Question

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

Answer 1

Answer:

The temperature on the 5th day was of -9ºC.

Step-by-step explanation:

Mean of a data-set

The mean of a data-set is the sum of all values in the data-set divided by the number of values.

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

This means that during the first 4 days, the sum of the temperatures was 4*1 = 4ºC.

The mean temperature for the first 5 days in January was -1°C.

First 4 days: Sum of 4º

5th day: Temperature of x.

The mean is -1, so:

$-1 = \frac{4 + x}{5}$

$x + 4 = -5$

$x = -9$

The temperature on the 5th day was of -9ºC.