Question
If $\sum_{j=1}^{21} a_{j}=693$, where $a_{1}, a_{2}, \ldots, a_{21}$, are in A.P., then $\sum_{i=0}^{10} a_{2 i+1}$ is(A) 361(B) 396(C) 363(D) data insufficient
Step 1
Given that $\sum_{j=1}^{21} a_{j}=693$, we can write this as $\frac{21}{2}(a_1 + a_{21}) = 693$. Show more…
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