/

Learn

Saturday, 31 October

/

JEE Main 2021 · MathsNumerical answerNumerical valueHardMulti-step

JEE Main 26 August 2021, Shift 1, Maths Q87

Question 87 of 90 in this shift, Maths question 27 of 30, Section B.

If

^1P_1+2\cdot{}^2P_2+3\cdot{}^3P_3+\ldots+15\cdot{}^{15}P_{15}={}^qP_r-s

,

0 \leq s \leq 1

, then

^{q+s}C_{r-s}

is equal to __________.

Official answer

136

NTA final key.

Chapter: Permutations and Combinations
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 108 of the 174 JEE Main shifts held from 2017 to 2026.