Arithmetic Progressions
CH05 Question Bank
CBSE_CH05_QUESTION_BANK
Grade 10
Question:
Find the middle term of the AP $1, 8, 15, \ldots, 505$.
Step-by-Step Solution
Key Concept: First find the total number of terms, then identify the middle one (using the average of first and last positions, since n is odd).
$a=1,d=7,l=505$. $505=1+(n-1)7\Rightarrow n-1=72\Rightarrow n=73$ (odd, so there is a single middle term at position $37$). [1.0 Mark]
$a_{37}=1+36(7)=1+252=253$. [1.0 Mark]
Correct Answer:
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