Please explain

[mgmt_gmat]

n is an integer between 10 and 99, is n< 80?
a. Sum of the two digits on n is a prime number
b. Each of the two digits of n is a prime number

OA later

[linkinpark]

n is an integer between 10 and 99, is n< 80?
a. Sum of the two digits on n is a prime number consider 43,52..they satisfy but 98(sum of digits = 17 a prime) > 80 so ignore a
b. Each of the two digits of n is a prime number a little tricky but I pick b, why? because each of digit if prime
the numbers will be like 57, 75, 73, 37,25,52... these will be <80, for rest of numbers from 79 till 99 either 1 or both digits will not be prime hence B is sufficient
OA later

[mohit11]

Tricky question,

n is an integer between 10 and 99, is n< 80?
a. Sum of the two digits on n is a prime number
b. Each of the two digits of n is a prime number


A) Not sufficient, 83 > 80, 38 <80


B) Since each of the two digits are a prime number, therefore, we can only consider 2, 3, 5, 7 and the largest number formed using these digits will be 77 which is less than 80, so B


But since you already knew this, i am guessing the answer is not B. Whats the OA?

[mohit11]

Oh i thought Linkingpark was mgmt_gmat, Apologies, OA please

[ajith]

n is an integer between 10 and 99, is n< 80?
a. Sum of the two digits on n is a prime number
b. Each of the two digits of n is a prime number

OA later

Prime number between 10-100 are
11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97

a) insufficient - (83 and 61) both have sum of digits as prime numbers
b) 23,37,29,53 and 73 follow this; all of them are under 80 hence n<80; sufficient

B

[sars72]

n is an integer between 10 and 99, is n< 80?
a. Sum of the two digits on n is a prime number
b. Each of the two digits of n is a prime number

OA later

Prime number between 10-100 are
11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97

a) insufficient - (83 and 61) both have sum of digits as prime numbers
b) 23,37,29,53 and 73 follow this; all of them are under 80 hence n<80; sufficient
B

statement 1 only says that the sum of the digits is a prime number. You seem to have mistaken it as "n is a prime number and sum of digits is also prime number". So, from statement 1, the possibilites are not limited to 83 n 61 coz n need not be prime.

[ajith]

statement 1 only says that the sum of the digits is a prime number. You seem to have mistaken it as "n is a prime number and sum of digits is also prime number". So, from statement 1, the possibilites are not limited to 83 n 61 coz n need not be prime.

Well technically it doesn't matter what I thought, it is a perfectly valid combination (83 and 61)to disprove the contention that we can determine whether the number is less than or greater than 80. One of the number is more than 80 and the other is less than 80.

We need only 1 example to disprove a contention, to prove it 1 example would not be sufficient. Possibilities are not limited to 83 and 61, I agree, but, I just needed one example and it works out perfectly well. Nowhere do I mention that, it is the only combination possible