Data Sufficiency

Hello everyone!

I'm going over the first manual of MGMAT on Number properties (4th edition).
On page 100 there is an example of a data sufficiency problem that talks about the strategy of testing numbers.

The question lets us know that the possible answer is n=1, n=2, n=3 or n=4. It is a value question. Statement 1 says that n=2k+1 where k is an integer. The text then explains, and I agree, that the expression on statement 1 tells us that n is any odd number and therefore it is inconclusive about the value of n, since it can be either 1 or 3.

However, how can one obtain n=1 from the expression 2k+1??...I assumed that statement 1 would be sufficient because n=3 would be the only odd number to verify the expression n=2k+1 amongst the possible values of n.

Thanks!

Hey Gmf,

n = 2k + 1. n can be one when k = 0 because K is defined as integer.

Re-iterating answer from MGMAT.

1) n = 2k + 1
2) n is a prime number

Lets look at statement 2. n is a prime, this is eliminated cos 2 and 3 both are prime. We do not have a unique value for n.

n = 2k + 1 => n is a odd number. now we have 1 and 3 in the list of 1,2,3,4.

Now combine 1 and 2. n is prime and n is odd. Only 3 is the intersection of the answer choices.

Thanks
HK

Hi xtremecoder 007!
Thanks for the reply. I thought about k=0 but somehow didn't considered it as an integer. Now it makes sense!


GMF