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JEE Main 202229 JulyMorning Shift
Exam
JEE Main
Year
2022
Date
29 July
Shift
Morning Shift
Subject
Mathematics
Chapter
Probability

JEE Main 2022 · 29 July · Morning Shift · Mathematics · Probability

Let S = \ 1, 2, 3, , 2022\ . Then the probability, that a randomly...

Let S={1,2,3,…,2022}S = \left\{1, 2, 3, \ldots , 2022\right\}. Then the probability, that a randomly chosen number nn from the set SS such that HCF(n,2022)=1HCF\left(n, 2022\right) = 1, isLet S = \ 1, 2, 3, , 2022\ . Then the probability, that a randomly chosen number n from the set S such that HCF(n,

Options

  1. A1281011\dfrac{128}{1011}
  2. B1661011\dfrac{166}{1011}
  3. C127337\dfrac{127}{337}
  4. D112337\dfrac{112}{337}

Correct answer

D. 112337\dfrac{112}{337}

Step-by-step solution

Given,

S={1,2,3,…,2022}S = \left\{1, 2, 3, \ldots , 2022\right\}

So, total number of elements=2022= 2022

Now factors of 2022=2×3×3372022 = 2 \times 3 \times 337

Now HCF(n,2022)=1HCF \left(n, 2022\right) = 1 is feasible only when the value of 'nn' and 20222022 has no common factor.

Now let A=A =Number which are divisible by 22 from \left\{1, 2, 3, . . . 2022\right\}</p><p>So,</p><p>So,n\left(A\right) = 1011</p><p>Nowlet</p><p>Now letB =NumberwhicharedivisiblebyNumber which are divisible by3byby3from(1,2,3,...2022)from \left(1, 2, 3, . . . 2022\right)

So, n(B)=674n\left(B\right) = 674

Now A∩B=A \cap B =Number which are divisible by 66

Now from \left\{1, 2, 3, . . . 2022\right\}numbermultipleofnumber multiple of6areare6, 12, 18, . . . . 2022</p><p>So,</p><p>So,n\left(A \cap B\right) = 337</p><p>Nowapplyingtheformulaweget,</p><p>Now applying the formula we get,n\left(A \cup B\right) = n\left(A\right) + n\left(B\right) - n\left(A \cap B\right)</p><p></p><p>= 1011 + 674 - 337</p><p></p><p>= 1348</p><p>Nowlet</p><p>Now letC =NumberwhichdivisiblebyNumber which divisible by337from{1,.....1022}from \left\{1, . . . . . 1022\right\}

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

Total elements which are divisible by 22 or 33 or 337=1348+2=1350337 = 1348 + 2 = 1350

Favourable cases=elements which are neither divisible by 2,32, 3 or 337337

=2022−1350=672= 2022 - 1350 = 672

Required probability=6722022=112337= \dfrac{672}{2022} = \dfrac{112}{337}

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