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# If n is an integer between 10 and 99. Is n < 80?

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Joined: 04 Feb 2011
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If n is an integer between 10 and 99. Is n < 80?  [#permalink]

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11 Feb 2011, 01:48
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77% (01:38) correct 23% (01:35) wrong based on 148 sessions

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If n is an integer between 10 and 99. Is n < 80?

(1) The sum of the two digits of n is a prime number.

(2) Each of the two digits of n is a prime number.
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Re: data sufficiency prime numbers  [#permalink]

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11 Feb 2011, 02:05
1
1) The sum of two digits of n is prime number
83 and 38 are two such examples; one > 80 and another less than 80.
Not sufficient.

2) Each of two digits of n is prime number
All numbers >= 80 contain either 8 or 9 in tens place; both of which are not prime.
So the number must be less than 80.
Sufficient.

Ans: "B"
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Re: data sufficiency prime numbers  [#permalink]

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11 Feb 2011, 02:25
please explain the 2) with examples
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Re: data sufficiency prime numbers  [#permalink]

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11 Feb 2011, 03:39
Moved to DS subforum.

Lolaergasheva wrote:
If n is an integer btween 10 and 99. Is n < 80?
1) The sum of two digits of n is prime number
2) Each of two degits of n is prime numer

If n is an integer between 10 and 99. Is n < 80?

(1) The sum of the two digits of n is a prime number. Clearly insufficient: for example 83>80 and 38<80.

(2) Each of the two digits of n is a prime number --> max one digit prime is 7, thus max value of n is 77, which is less than 80. Sufficient.

 ! Please post PS questions in the PS subforum: gmat-problem-solving-ps-140/Please post DS questions in the DS subforum: gmat-data-sufficiency-ds-141/No posting of PS/DS questions is allowed in the main Math forum.

Also: DO NOT reword the question, copy EXACTLY as it is in the source.
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Re: If n is an integer between 10 and 99. Is n < 80?  [#permalink]

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26 Jan 2017, 05:22
(1) the sum of the digits is prime.

We can pick n=83, since 8+3=11 which is prime.

Is 83 < 80? No.

We can also pick 32, since 3+2=5 which is prime.

Is 32 < 80? Yes.

No and Yes, therefore insufficient.

(2) Each of the digits is prime.

Well, that means that each digit is either 2, 3, 5 or 7. In other words, the biggest possible value for n is 77. Therefore, every possible value for n will be less than 80: sufficient.

(1) is insufficient, (2) is sufficient: choose (b).
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Re: If n is an integer between 10 and 99. Is n < 80?  [#permalink]

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28 Jun 2018, 01:11
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Re: If n is an integer between 10 and 99. Is n < 80? &nbs [#permalink] 28 Jun 2018, 01:11
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