Highly selective Backlog Qs for JEE MainMathematicsSequences and Series

In the sequence, (1,2,3),(4,5,6),(7,8,9,10) of sets, the sum of elements in the 50th set is

Options

A62525
B65225
C56255
D557625

Correct answer

A. 62525

Step-by-step solution

First term of each sets are 1,2,4,7, Let aligned & S=1+2+4+7+ +T_n & S=1+2+4+ +T_n aligned On subtracting, we get aligned & 0=1+1+2+3+ -T_n & T_n=1+(1+2+3+ (n-1) terms ) & T_n=1+ (n-1) n 2 & T₅₀=1+ 49 50 2 & T₅₀=1226 & aligned First term of 50th set is 1226 , therefore series is 1226,1227, 50 terms S= 50 2 [2 1226+49]=62525

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