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Question

If the mean of a set of 7 observations is 10 and the mean of a set of 3 observations is 5, then what is the combined mean?

This question was previously asked in
CDS 2 2026 Maths Question Paper (13-Sep-2026)
The correct answer is

8.5

Sum of the 7 observations \(=7\times10=70\). Sum of the 3 observations \(=3\times5=15\). Combined mean \(=\dfrac{70+15}{7+3}=\dfrac{85}{10}=8.5\).

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