OG Quantitative (Green) #86

[mdavis]

Could someone explain the answer to this question?

Can the positive integer n be written as the sum of two different positive prime numbers?

(1) n is greater than 3.
(2) n is odd.

[peddisetty]

Lets take 4(3+1), 5(3+2),6(5+1), 7(5+2), 8(5+3), 9(7+2), 10(7+3) can all be written as sum of two different prime nos. But 2 cant be written as sum of two different primes.

In A, we have n>3, so its sufficient.

B, is not sufficient. Since 1 is odd, but cant be written as sum of two different primes.

So, the answer is A.

[raptor84]

IMO its E.

Take the number 11. This cant be expressed as a sum of two +ve prime numbers right.

So E.

Whats the OA?

[mdavis]

OA is E. The explanation in the book is confusing to me.

[sacx]

I think it should be E

1. n > 3

Lets say its 11 - cannot be expressed as a sum of prime numbers

2. n is odd

Same example as above can be used

Comine 1 & 2, n = 11 and it fails again