Question

The mean temperature for the first 4 days in January was 8°C. The mean temperature for the first 5 days in January was 7°C. What was the temperature on the 5th day? SOMEONE HELP FIRST ANSWER BRAINLIEST THIS TIME I PROMISE LOL

Answer 1

Answer:

The temperature of the 5th day was 3°C

Step-by-step explanation:

Mean temperature of the first 4 days = 8°C

Note that:

Mean = Sum of temperatures ÷ number of days

∴ 8 = sum of temperature ÷ 4

$= 8 = \frac{sum\ of\ temperatures}{4}$

$= sum\ of\ temperatures\ = 8\ \times\ 4 = 32$

Therefore the sum of the first 4 days = 32

Let the temperature of the next day (the fifth day) be m

Hence,

sum of the temperatures of first 5 days = 32 + m - - - - (1)

Next, the sum of the first 5 days can be calculated from the given average of the first 5 days as follows:

Mean temperature of the first 5 days = 7

$Mean = \frac{sum\ of\ temperatures}{number \ of\ days}\\\\7 = \frac{sum\ of\ temperatures}{5} \\sum\ of\ temperatures\ = \ 7\ \times\ 5\ = 35\\sum\ of\ temperature\ of\ the\ first\ 5\ days\ =\ 35 - - - - - (2)$

Now, you will notice that equation (1) = equation (2)

∴ 32 + m = 35

m = 35 - 32 = 3

therefore, the temperature of the 5th day was 3°C