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If x is a prime number, what is the value of x?

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Bunuel
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If x is a prime number, what is the value of x? [#permalink] New post   26 Jun 2023, 01:30
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49% (01:11) correct 51% (01:08) wrong based on 53 sessions
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If x is a prime number, what is the value of x?

(1) There are three prime numbers between 11 and x, exclusive
(2) x + 1 is a prime number


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B
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8.toastcrunch
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If x is a prime number, what is the value of x? [#permalink] New post   Updated on: 26 Jun 2023, 02:25
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Statement (1): There are three prime numbers between 11 and x, exclusive.

so x can be 2 or 23, Not sufficient

Statement (2): x + 1 is a prime number
It is given that x is prime number and there is only one possibility that x is a prime and x+1 is also a prime , x=2 , sufficient

Answer is option B.

Originally posted by 8.toastcrunch on 26 Jun 2023, 01:58.
Last edited by 8.toastcrunch on 26 Jun 2023, 02:25, edited 1 time in total.
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Re: If x is a prime number, what is the value of x? [#permalink] New post   26 Jun 2023, 02:11
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(1) Only
x could be 2 or 23
Not sufficient.

(2) Only
x must be 2.
Because other prime numbers n are all odd, so n+1 is even and cannot be another prime number.
Sufficient.

The answer is thus (B).
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Re: If x is a prime number, what is the value of x? [#permalink] New post   29 Jun 2023, 01:48
zhanbo wrote:
(1) Only
x could be 2 or 23
Not sufficient.

(2) Only
x must be 2.
Because other prime numbers n are all odd, so n+1 is even and cannot be another prime number.
Sufficient.

The answer is thus (B).

sir can you pls explain how x can be 2 or 23 in statement 1

between 11 13 17 19 23
x can be 23 only
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Re: If x is a prime number, what is the value of x? [#permalink] New post   29 Jun 2023, 01:52
Rabab36 wrote:
zhanbo wrote:
(1) Only
x could be 2 or 23
Not sufficient.

(2) Only
x must be 2.
Because other prime numbers n are all odd, so n+1 is even and cannot be another prime number.
Sufficient.

The answer is thus (B).

sir can you pls explain how x can be 2 or 23 in statement 1

between 11 13 17 19 23
x can be 23 only


Starting from 2,
3, 5, 7
11

There are three prime numbers between 2 and 11.
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Re: If x is a prime number, what is the value of x? [#permalink] New post   30 Jun 2023, 03:15
I don't think the question is well constructed. It is an easy question but statement 1 makes it difficult to understand.

1) There are three prime numbers between 11 and x, exclusive.

This statement reads that we need to find 3 prime factors between 11 and x. So, normally a person will solve it as follows:

11, 13, 17, 19, 23.

X=23.

But however, as per experts, it can also be 2, 3, 5, 7, 11. X=2.

I highly doubt that this type of question (poorly constructed) will come in the actual exam.
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Re: If x is a prime number, what is the value of x? [#permalink]
30 Jun 2023, 03:15
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Bunuel
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