Solved UPSC CDS/OTA Question
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Q · Average Medium · 45s
The average of 9 articles is 79. The average of the first 2 articles is 75. If the average of the next 4 articles is 87. If the 8th article is 5 more than the 7th article and 1 more than the 9th article. The calculated 9th observation?
TopicAverage
Question Typemultiple choice
DifficultyMedium
Marking+1 / −0.33
Test Duration30 min
Step-by-Step Solution
The complete worked solution.
Every step explained — no skipped algebra.
Sum of all 9 articles = 9 X 79 = 711
Sum of first 2 articles = 2 X 75 = 150
Sum of next 4 articles = 4 X 87 = 348
7th article = x + 1, 8th article = x + 6, 9th
article = x + 5
x + 1 + x + 6 + x + 5 = 213
3x = 201
x = 67
Then, 9th article = x + 5 = 72
Final Answer: Option C — 70