JEE Main 2020 · MathsMultiple choiceSingle correctMediumApplication

JEE Main 8 January 2020, Shift 1, Maths Q68

Question 68 of 75 in this shift, Maths question 18 of 25, Section A.

Let A and B be two independent events such that

P(A)=\frac{1}{3}

and

P(B)=\frac{1}{6}

. Then, which of the following is TRUE ?

(1) $P(A/(A\cup B))=\frac{1}{4}$
(2) $P(A/B)=\frac{2}{3}$
(3) $P(A/B')=\frac{1}{3}$ Official answer
(4) $P(A'/B')=\frac{1}{3}$

Official answer

Option 3

NTA final key (Jan 2020).

Chapter: Probability
Topic: Conditional Probability
Idea tested: Conditioning on a Complementary Event

Same topic in other shifts

All Conditional Probability questions

5 Apr 2026, Shift 1 · Q7A letter is known to have arrived by post either from KANPUR or from ANANTPUR. On the envelope just two consecutive letters AN are…MediumSingle correct
5 Apr 2026, Shift 2 · Q8The probabilities that players A and B of a team are selected for the captaincy for a tournament are 0.6 and 0.4, respectively. If A is…EasySingle correct
6 Apr 2026, Shift 2 · Q9A bag contains 6 blue and 6 green balls. Pairs of balls are drawn without replacement until the bag is empty. The probability that each…MediumSingle correct
8 Apr 2025, Shift 2 · Q9If $A$ and $B$ are two events such that $P(A) = 0.7$ , $P(B) = 0.4$ and $P(A \cap \overline{B}) = 0.5$ , where $\overline{B}$ denotes the…MediumSingle correct
29 Jan 2024, Shift 1 · Q19A fair die is thrown until 2 appears. Then the probability, that 2 appears in even number of throws, isMediumSingle correct
31 Jan 2024, Shift 1 · Q19Two marbles are drawn in succession from a box containing 10 red, 30 white, 20 blue and 15 orange marbles, with replacement being made…EasySingle 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 42 of the 174 JEE Main shifts held from 2017 to 2026.