The arithmetic mean of two numbers is 14. One of the numbers is 12.4. Find another number.

From the condition it is known that the arithmetic mean of two numbers is 14. It is also known that one of the numbers is 12.4. In order to find another number, compose and solve the equation.

Let’s denote the second number with the variable x.

The arithmetic mean of two numbers is equal to the sum of these numbers divided by 2 (their number).

(a + b) / 2 = m;

Substitute the known values and solve the resulting equation:

(12.4 + x) / 2 = 14;

12.4 + x = 14 * 2;

12.4 + x = 28;

We are looking for a variable as an unknown term.

x = 28 – 12.4;

x = 15.6 second number.