Arithmetic Progressions
RD Sharma
CBSE
Grade 10
Question:
If $p, q, r$ are in A.P., then $q$ is equal to:
(a) $\dfrac{p + r}{2}$
(b) $p + r$
(c) $\dfrac{p - r}{2}$
(d) $\sqrt{pr}$
Step-by-Step Solution
Key Concept: Arithmetic Mean $q = \dfrac{p + r}{2}$.
$q - p = r - q \Rightarrow 2q = p + r \Rightarrow q = \dfrac{p + r}{2}$. [1.0 Mark]
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🎯 Official CBSE Marking Scheme:
Selecting Arithmetic Mean formula: 1.0 Mark
Correct Answer: $\dfrac{p + r}{2}$
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