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Friday, 9 October

JEE Main 2023 · MathsMultiple choiceSingle correctHardMulti-step

JEE Main 11 April 2023, Shift 1, Maths Q3

Question 3 of 90 in this shift, Maths question 3 of 30, Section A.

Consider ellipses Ek:kx2+k2y2=1, k=1,2,…,20E_k : kx^2 + k^2y^2 = 1,\ k = 1, 2, \ldots, 20. Let CkC_k be the circle which touches the four chords joining the end points (one on minor axis and another on major axis) of the ellipse EkE_k. If rkr_k is the radius of the circle CkC_k, then the value of ∑k=1201rk2\sum_{k=1}^{20} \frac{1}{r_k^2} is
  1. (1)2870
  2. (2)3080Official answer
  3. (3)3210
  4. (4)3320

Official answer

Option 2

NTA final key.

Chapter
Conic Sections
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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 42 of the 174 JEE Main shifts held from 2017 to 2026.