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Saturday, 31 October

JEE Main 2020 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 2 September 2020, Shift 2, Maths Q56

Question 56 of 75 in this shift, Maths question 6 of 25.

Let n > 2 be an integer. Suppose that there are n Metro stations in a city located along a circular path. Each pair of stations is connected by a straight track only. Further, each pair of nearest stations is connected by blue line, whereas all remaining pairs of stations are connected by red line. If the number of red lines is 99 times the number of blue lines, then the value of n is :
  1. (1)201201Official answer
  2. (2)200200
  3. (3)101101
  4. (4)199199

Official answer

Option 1

NTA final key (Sep 2020).

Chapter
Permutations and Combinations
Topic
Permutations and Combinations
Idea tested
Number of Diagonals in a Polygon

Same topic in other shifts

All Permutations and Combinations questions
  1. 2 Apr 2026, Shift 1 · Q6The number of seven-digit numbers, that can be formed by using the digits 1,2,3,51, 2, 3, 5 and 77 such that each digit is used at least once,…MediumSingle correct
  2. 2 Apr 2026, Shift 2 · Q7Let pnp_n denote the total number of triangles formed by joining the vertices of an nn-side regular polygon. If pn+1−pn=66p_{n+1} - p_n = 66,…EasySingle correct
  3. 4 Apr 2026, Shift 1 · Q4The number of functions f:{1,2,3,4}→{a,b,c}f:\{1,2,3,4\}\to\{a,b,c\}, which are not onto, is:EasySingle correct
  4. 4 Apr 2026, Shift 1 · Q8The number of ways, of forming a queue of 44 boys and 33 girls such that all the girls are not together, is:EasySingle correct
  5. 4 Apr 2026, Shift 2 · Q17Let A={(a,b,c):a,b,cA=\{(a,b,c):a,b,c are non-negative integers and a+b+2c=22}a+b+2c=22\}. Then n(A)n(A) is equal to:MediumSingle correct
  6. 5 Apr 2026, Shift 1 · Q21Let A={1,2,3,4,5,6}A = \{1, 2, 3, 4, 5, 6\}. The number of one-one functions f:A→Af: A \to A such that f(1)≥3f(1) \geq 3, f(3)≤4f(3) \leq 4 and f(2)+f(3)=5f(2) + f(3) = 5,…MediumNumerical value

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.