JEE Main 2021 · MathsMultiple choiceSingle correctEasyCalculation

JEE Main 4 August 2021, Shift 1, Maths Q77

Question 77 of 90 in this shift, Maths question 17 of 30, Section A.

Four persons work independtly of each other on a task. If the probabilities that they will complete the task are :

\frac{1}{2},\frac{1}{3},\frac{1}{4}

and

\frac{1}{5}

, then the probability, that at least one of them will complete it, is

(1) $0.2$
(2) $0.8$ Official answer
(3) $0.4$
(4) $0.6$

Official answer

Option 2

NTA final key.

Chapter: Probability
Topic: Conditional Probability
Idea tested: Independence Criterion

Same idea in other shifts

Asked 5× in all

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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.