JEE Main 2022 · 26 Jul · Shift 1 · Mathematics Q23

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MathematicsInteger+4 / -1Question 23 of 90

The series of positive multiples of 3 is divided into sets : {3}, {6, 9, 12}, {15, 18, 21, 24, 27}, ... Then the sum of the elements in the 11 $^{\text{th}}$ set is equal to ______.

Your answer

Answer and worked solution

Official answer: 6993

Set sizes 1, 3, 5, ...: the first ten use 100 terms, so the 11th has 21 terms, $3\times101$ to $3\times121$ .

Sum $3\cdot\frac{21}2(101+121)=6993$ .

Answer: 6993

Topics:Arithmetic progression

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JEE Main 2022 · 26 Jul · Shift 1, Mathematics question 23