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Saturday, 31 October

JEE Main 2021 · MathsNumerical answerNumerical valueHardMulti-step

JEE Main 24 February 2021, Shift 1, Maths Q85

Question 85 of 90 in this shift, Maths question 25 of 30, Section B.

Let A={n∈N:n is a 3-digit number}A = \{n \in N : n \text{ is a 3-digit number}\} B={9k+2:k∈N}B = \{9k + 2 : k \in N\} and C={9k+l:k∈N}C = \{9k + l : k \in N\} for some ll (0<l<90 < l < 9) If the sum of all the elements of the set A∩(B∪C)A \cap (B \cup C) is 274×400274 \times 400, then ll is equal to ___________.

Official answer

5

NTA final key.

Chapter
Relations and Functions
Topic
Sets and Relations
Idea tested
Set Operations

Same idea in other shifts

Asked 2× in all
  1. 3 Aug 2021, Shift 1 · Q61If S1={x∈R:x2+∣x∣−2=0}S_1 = \{x \in \mathbb{R} : x^2 + |x| - 2 = 0\} and S2={x∈R:x2+x−2=0}S_2 = \{x \in \mathbb{R} : x^2 + x - 2 = 0\}, thenEasySingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.