Q1. [1]
For the data 2, 9, $x + 6$, $2x + 3$, 5, 10, 5; if the mean is 7, then the value of $x$ is :
- A $9$
- B $6$
- C $5$
- D $3$
Previously asked in CBSE board exam
2024 30/5/1 Q6
Generated by claude-sonnet-4-6 · 2026-06-15 10:33 · grounding rag
Model Answer
Option (D) 3
Mean = $\dfrac{2 + 9 + (x+6) + (2x+3) + 5 + 10 + 5}{7} = 7$
$\Rightarrow 2x + 40 = 49 \Rightarrow 2x = 9$...
Recalculating: $2 + 9 + x + 6 + 2x + 3 + 5 + 10 + 5 = 3x + 40$
$\dfrac{3x + 40}{7} = 7 \Rightarrow 3x + 40 = 49 \Rightarrow 3x = 9 \Rightarrow x = 3$
Answer: D) 3
Explanation
Sum all terms: $2 + 9 + (x+6) + (2x+3) + 5 + 10 + 5 = 3x + 40$. Set $\frac{3x+40}{7} = 7$, solve to get $x = 3$. Watch out for carefully collecting like terms ($x + 2x = 3x$) — a common slip.
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