JEE Main 2019 — Probability Question with Solution
From: JEE Main 2019 (Online) 9th January Evening Slot
Question
An urn contains 5 red and 2 green balls. A ball is drawn at random from the urn. If the drawn ball is green, then a red ball is added to the urn and if the drawn ball is red, then a green ball is added to the urn; the original ball is not returned to the urn. Now, a second ball is drawn at random from it. The probability that the second ball is red, is :
Choose an option
Show full solutionCorrect option: D
Correct answer
D
Step-by-step explanation
5 Red and 2 green balls
P(one red ball) =
P(one green ball) =
Case I :
If drawn ball is green than a red ball is added
P (red ball) =
Case II :
If drawn ball is red than a green ball is added
P (red ball) =
P (2nd red ball) = =
P(one red ball) =
P(one green ball) =
Case I :
If drawn ball is green than a red ball is added
P (red ball) =
Case II :
If drawn ball is red than a green ball is added
P (red ball) =
P (2nd red ball) = =
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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.