The average of 20 numbers is 18 while the average of 18 numbers is 20. What is the average of the 38

Discussion in 'Calculator Requests' started by math_celebrity, Nov 24, 2018.

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  1. math_celebrity

    math_celebrity Administrator Staff Member

    The average of 20 numbers is 18 while the average of 18 numbers is 20. What is the average of the 38 numbers?

    The average of averages is found by getting the sum of both groups of numbers and dividing by the count of numbers.

    Calculate the sum of the first group of numbers S1:
    Average = S1 / n1
    18 = S1 / 20
    S1 = 20 * 18
    S1 =360

    Calculate the sum of the second group of numbers S2:
    Average = S2 / n2
    20 = S2 / 18
    S2 = 18 * 20
    S2 =360

    Our average of averages is found by the following:
    A = (S1 + S2)/(n1 + n2)
    A = (360 + 360)/(20 + 18)
    A = 720/38
    A = 18.947
     

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