Let S = 1 , 2 , 3 , … , 2022 . Then the probability, that a randomly chosen number n from the set S…

Let S=1,2,3,,2022. Then the probability, that a randomly chosen number n from the set S such that HCFn,2022=1, is
  1. 1281011
  2. 1661011
  3. 127337
  4. 112337

Solution

Given,

S=1,2,3,,2022

So, total number of elements=2022

Now factors of 2022=2×3×337

Now HCFn,2022=1 is feasible only when the value of 'n' and 2022 has no common factor.

Now let A=Number which are divisible by 2 from 1,2,3,...2022

So, nA=1011

Now let B=Number which are divisible by 3by 3 from 1,2,3,...2022

So, nB=674

Now AB=Number which are divisible by 6

Now from 1,2,3,...2022 number multiple of 6 are 6,12,18,....2022

So, nAB=337

Now applying the formula we get, nAB=nA+nB-nAB

=1011+674-337

=1348

Now let C=Number which divisible by 337 from 1,.....1022

Total elements which are divisible by 2 or 3 or 337=1348+2=1350

Favourable cases=elements which are neither divisible by 2,3 or 337

=2022-1350=672

Required probability=6722022=112337

Asked in: JEE Main 2022 (29 Jul Shift 1)

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