Question
The average of sixty numbers is 70 while the average of
first thirty numbers and last thirty numbers is 75 and 85, respectively. Find the thirtieth term.Solution
ATQ,
Sum of sixty numbers = (60 × 70) = 4200
Sum of the first thirty numbers = (30 × 75) = 2250
Sum of the last thirty numbers = (30 × 85) = 2550
So, thirtieth term = 2250 + 2550 - 4200 = 600
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