JEE Main 2020 — Probability Question with Solution
From: JEE Main 2020 (Online) 4th September Evening Slot
Question
In a game two players A and B take turns in throwing a pair of fair dice starting with player A and total of scores on the two dice, in each throw is noted. A wins the game if he throws total a of 6 before B throws a total of 7 and B wins the game if he throws a total of 7 before A throws a total of six. The game stops as soon as either of the players wins. The probability of A winning the game is :
Choose an option
Show full solutionCorrect option: D
Correct answer
D
Step-by-step explanation
Sum total 6 = {(1,5)(2,4)(3,3)(4,2)(5,1)}
Sum total 7 = {(1,6)(2,5)(3,4)(4,3)(5,2)(6,1)}
=
Game ends and A wins if A throws 6 in 1st throw or A don’t throw 6 in 1st throw, B don’t throw 7 in 1st throw and then A throw 6 in his 2 nd chance and so on.
P(A) = A + +
= .....
=
=
=
Sum total 7 = {(1,6)(2,5)(3,4)(4,3)(5,2)(6,1)}
=
Game ends and A wins if A throws 6 in 1st throw or A don’t throw 6 in 1st throw, B don’t throw 7 in 1st throw and then A throw 6 in his 2 nd chance and so on.
P(A) = A + +
= .....
=
=
=
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This is a previous-year question from JEE Main 2020, 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.