Important Average Formulas

  1. Average is also known as Mean. And it is calculated by dividing the sum of elements in an observation by the number of elements in that observation.
    Average =
    x1 + x2 + x3 + ... xn

    N
    = Σxi

    N

  2. Suppose a man driving a car covers a certain distance at x m/s and the same distance at y m/s. So, to get the average speed for the whole trip, use this formula-
    2xy

    x + y
    m/s
  3. Let's apply the above formula in an example-
    Suppose, the average age of a father and his son is 25. If the age of a father is 40, then what is the age of his son?
    We know that, Mean =
    Σxi

    N

    Let the son's age be x. Here the value of N is 2.
    25 =
    40 + x

    2

    x = 10
    ∴ The son's age is 10 years.