Question
The average of fifty numbers is 55 while the average of
first twenty-five numbers and last twenty-five numbers is 60 and 70, respectively. Find the twenty-fifth term.Solution
ATQ,
Sum of fifty numbers = (50 × 55) = 2750
Sum of the first twenty-five numbers = (25 × 60) = 1500
Sum of the last twenty-five numbers = (25 × 70) = 1750
So, twenty-fifth term = 1500 + 1750 - 2750 = 500
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