Question
The average of the first three numbers is twice the average
of the next six numbers. If the average of all nine numbers is 20, then find the sum of the last six numbers.Solution
ATQ,
Let the sum of the last six numbers be 'n'.
So, (sum of the first three numbers) ÷ 3 = 2 × (n/6)
Or, sum of the first three numbers = 2n
So, (n + 2n) ÷ 9 = 20
Or, 3n = 180
Or, n = 60
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