99 Percentile Qs Bank for JEE MainMathematicsSequences and Series

If the average of the first n numbers in the sequence 148,146,144, , is 125 , then n is equal to

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Correct answer

B. 24

Step-by-step solution

Given sequence 148,146,144, and average is 125. aligned S_n & = n 2 [2 148+(n-1)(-2)] [ d=-2] & = n 2 [296-2 n+2] & =n[148-n+1]=n[149-n] aligned Hence, 125= n[149-n] n aligned & 125=149-n & n=149-125=24 & aligned

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