JEE Main 2020 — Probability Question with Solution
From: JEE Main 2020 (Online) 6th September Morning Slot
Question
Out of 11 consecutive natural numbers if three numbers are selected at random (without repetition), then the probability that they are in A.P. with positive common difference, is :
Choose an option
Show full solutionCorrect option: B
Correct answer
B
Step-by-step explanation
Out of 11 consecutive natural numbers either
6 even and 5 odd numbers or 5 even and 6
odd numbers.
Let, E = Even
O = Odd
Case-1 :
E, O, E, O, E, O, E, O, E, O, E
2b = a + c Even
Both a and c should be either even or odd.
P = =
Case -2 :
O, E, O, E, O, E, O, E, O, E, O
P = =
Total probability = + =
Let, E = Even
O = Odd
Case-1 :
E, O, E, O, E, O, E, O, E, O, E
2b = a + c Even
Both a and c should be either even or odd.
P = =
Case -2 :
O, E, O, E, O, E, O, E, O, E, O
P = =
Total probability = + =
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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.