Solved UPSC CDS/OTA Question
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Q · Average Medium · 45s
The average of 9 observations is 87. If the average of the first 5 observations is 79 and the average of the next three is 92. Find the 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 9 observations = 9 X 87 = 783
Sum of first 5 observation = 5 X 79 = 395
Sum of next 3 observation = 3 X 92 = 276
9th observation = 783 - 395 - 276 = 112
Final Answer: Option B — 87