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If n is an integer between 10 and 99, is n < 80?
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15 Jan 2012, 22:49
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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. I know this must be easy. The answer is B (statement 2 is sufficient alone, while statement 1 is not). Doesn't that lead to tons of possible values of n?
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Re: If n is an integer between 10 and 99, is n < 80?
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16 Jan 2012, 02:25
vandygrad11 wrote: 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. I know this must be easy. The answer is B (statement 2 is sufficient alone, while statement 1 is not). Doesn't that lead to tons of possible values of n? If n is an integer between 10 and 99. Is n < 80?Notice that n is an integer between 10 and 99 means that n is twodigit integer.(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 > greatest one digit prime is 7, thus max value of n is 77, which is less than 80. Sufficient. Answer: B. vandygrad11 wrote: I am lost on this one. Prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, etc. There are several values that satisfy the conditions of 10>n>80 while both digits are prime numbers, for instance 23, 32, 57, etc. Is that the reason that we can eliminate #2? Similarly, not to sound stupid, but is 67 then the only integer that meets the conditions of #1? Thanks. We are told that n is a twodigit integer and each of these two digits is a prime, so n can be: 22, 23, 25, 27, ... and as greatest one digit prime is 7, thus max value of n is 77. As what n could be taking in account statement (1): 23 > 2+3=5=prime; 25 > 2+5=7=prime; 29 > 2+9=11=prime; ... Hope it's clear.
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Re: If n is an integer between 10 and 99, is n < 80?
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15 Jan 2012, 23:28
vandygrad11 wrote: 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. I know this must be easy. The answer is B (statement 2 is sufficient alone, while statement 1 is not). Doesn't that lead to tons of possible values of n? 1. let n be 67 then 6+7 = 13 (prime) and n < 80 but if n is 89 then 8+9 =17 (prime) and n >80. hence insuff 2. 8 and 9 are not prime so n < 80 as no value above 80 satisfies stmnt 2 hence suff B



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Re: If n is an integer between 10 and 99, is n < 80?
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15 Jan 2012, 23:38
kp1811 wrote: vandygrad11 wrote: 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. I know this must be easy. The answer is B (statement 2 is sufficient alone, while statement 1 is not). Doesn't that lead to tons of possible values of n? 1. let n be 67 then 6+7 = 13 (prime) and n < 80 but if n is 89 then 8+9 =17 (prime) and n >80. hence insuff 2. 8 and 9 are not prime so n < 80 as no value above 80 satisfies stmnt 2 hence suff B I am lost on this one. Prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, etc. There are several values that satisfy the conditions of 10>n>80 while both digits are prime numbers, for instance 23, 32, 57, etc. Is that the reason that we can eliminate #2? Similarly, not to sound stupid, but is 67 then the only integer that meets the conditions of #1? Thanks.



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Re: If n is an integer between 10 and 99, is n < 80?
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16 Jan 2012, 02:21
vandygrad11 wrote: kp1811 wrote: vandygrad11 wrote: 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. I know this must be easy. The answer is B (statement 2 is sufficient alone, while statement 1 is not). Doesn't that lead to tons of possible values of n? 1. let n be 67 then 6+7 = 13 (prime) and n < 80 but if n is 89 then 8+9 =17 (prime) and n >80. hence insuff 2. 8 and 9 are not prime so n < 80 as no value above 80 satisfies stmnt 2 hence suff B I am lost on this one. Prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, etc. There are several values that satisfy the conditions of 10>n>80 while both digits are prime numbers, for instance 23, 32, 57, etc. Is that the reason that we can eliminate #2? Similarly, not to sound stupid, but is 67 then the only integer that meets the conditions of #1? Thanks. 67 is not the only number for #1 we can have several numbers satisfying this condition like 23,32, 12, 21,43,34 also for stmnt 2 any number = or > than 80 will have 8 or 9 as ten's digit which are not prime and don't agree with stmnt 2



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Re: If n is an integer between 10 and 99, is n < 80?
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16 Jan 2012, 02:26
Just got this. Way easier than I was making it out to be. Thanks.



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Re: If n is an integer between 10 and 99, is n < 80?
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27 Nov 2015, 08:04
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.
92, 9+2=11, is 92 < 80? no 29, 2+9=11, is 11 < 80? yes
(2) Each of the two digits of n is a prime number.
Single digit primes are 2, 3, 5, 7. Any combination into a 2 digit number will be < 80
Answer: B



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Re: If n is an integer between 10 and 99, is n < 80?
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07 Jan 2017, 22:16
If we prove none of the number greater than 80 satisfy (1) or (2) , then we can answer the question.
from 81 to 98 inclusive : there are more than 1 number satisfying statement (1) , n could take multiple values(83,85 etc), hence (1) is insufficient. from 81 to 98 inclusive : there are no numbers which have both of the digits as prime, this satisfies (2), hence n must be less than 80.
Ans : B



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Re: If n is an integer between 10 and 99, is n < 80?
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03 Jul 2017, 03:27
looks easier than done during the test. why is that the easier questions also take more time in exam than when normally practicing



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If n is an integer between 10 and 99, is n < 80?
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11 Jul 2017, 06:54
geometric wrote: 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. I know this must be easy. The answer is B (statement 2 is sufficient alone, while statement 1 is not). Doesn't that lead to tons of possible values of n? 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.Lets take numbers: \(76  7 + 6 = 13 =\)Prime \(< 80\) \(85  8 + 5 = 13 =\)Prime \(> 80\) Hence, (1) ===== is NOT SUFFICIENT(2) Each of the two digits of n is a prime number.\(8\) & \(9\) are non prime numbers Hence, the only possibility of having both the digits as prime is when the number is \(< 80\) Hence, (2) ===== is SUFFICIENT Hence, Answer is BYou liked the answer? Appreciate with a Kudos
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Re: If n is an integer between 10 and 99, is n < 80?
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16 Sep 2018, 10:16
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Re: If n is an integer between 10 and 99, is n < 80? &nbs
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