Question

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

The mean temperature for the first 5 days in January was 3°C.
What was the temperature on the 5th day?

Answer 1

Explanation:

mean is average, so if we label the first through fifth days of january a-e we can solve it.

So average of the first four is (a+b+c+d)/4 = 1 and the first five is (a+b+c+d+e)/5 = 2. Since it's easy, let's get rid of the fraction in both.

(a+b+c+d)/4 = 1 and (a+b+c+d+e)/5 = 2

a+b+c+d = 4 and a+b+c+d+e = 10

Now, we know a+b+c+d is 4, so we can replace that in the second equation

a+b+c+d+e = 10

4 + e = 10

e = 6

ad since e is the fifth day, we know the temperature of it. Let me know if something here didn't make sense