JEE Main 2019MathematicsProbabilityEasyMCQ

JEE Main 2019 — Probability Question with Solution

JEE Main 2019 (08 Apr Shift 2)

Question

The minimum number of times one has to toss a fair coin so that the probability of observing at least one head is at least 90% is:

Choose an option

Show full solutionCorrect option: B
Correct answer
B4

Step-by-step explanation

Let a fair coin is tossed n times, then
P(at least one head) =1–P(all tails)
=1–12n>90100 (given)
⇒12n<1-90100=110
⇒2n>10
⇒n≥4

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About this question

This is a previous-year question from JEE Main 2019, covering the Probability chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.