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JEE Main 2023 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 8 April 2023, Shift 2, Maths Q17

Question 17 of 90 in this shift, Maths question 17 of 30, Section A.

If the probability that the random variable

X

takes values

x

is given by

P(X = x) = k(x + 1)3^{-x}

,

x = 0, 1, 2, 3, \ldots

, where

k

is a constant, then

P(X \geq 2)

is equal to

(1) $\frac{7}{18}$
(2) $\frac{11}{18}$
(3) $\frac{7}{27}$ Official answer
(4) $\frac{20}{27}$

Official answer

Option 3

NTA final key.

Chapter: Probability
Topic: Arithmetico-Geometric Series
Idea tested: AGP in Expected Value Scenarios

Same idea in other shifts

Asked 2× in all

25 Jul 2021, Shift 2 · Q70Let X be a random variable such that the probability function of a distribution is given by $P(X=0)=\frac{1}{2}$ , $P(X=j)=\frac{1}{3^j}$ …MediumSingle 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.