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Question: Answered & Verified by Expert
Let S be the sample space of all five digit numbers. If p is the probability that a randomly selected number from S, is a multiple of 7 but not divisible by 5, then 9p is equal to
MathematicsProbabilityJEE MainJEE Main 2022 (27 Jul Shift 1)
Options:
  • A 1.0146
  • B 1.2085
  • C 1.0285
  • D 1.1521
Solution:
1368 Upvotes Verified Answer
The correct answer is: 1.0285

Given, five-digit number,

So nS=total 5 digit number will be=9×104

Now let A: number is multiple of 7 but not divisible by 5

Smallest 5 digit divisible by 7 is 10003

Largest 5 digit divisible by 7 is 99995

Now by using nth term of A.P formula we have,

  99995=10003+n-17

n=12857

Now finding number which is divisible by 35

Again using A.P formula we have,

99995=10010+P-135

P=2572

Now number divisible by 7 but not by 35 are

12857-2572=10285

So, probability will be P=1028590000

And 9P=1.0285

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