vivekdixit07 wrote:
Hi,
Thanks for the explanation.
I m not so good in reasoning so I put the values and check.
For example in statement 1 I just entered the values of y as 1,3,5,7 and I get the values of X as 36,35,34,33 respect. After checking 4 - 5 values I got to know that the gcf is 1.
Please let me know if my strategy is good or not.
Thanks,
Try to understand this: If something generic is established, you can plug in specific examples and use them e.g. if I say, "All boys are crazy." I can say, "Tom, a boy, is crazy."
But the other way around may not always work. From certain examples, you cannot establish something generic. e.g. I cannot say, "Tom is crazy. Alfred is crazy. Ross is crazy. We can conclude that all boys are crazy."
Here, you have tried to do something like this which is not good. We cannot blindly plug in numbers and establish that GCD will be 1. We could have missed some pairs where GCD may not have been 1. What you can do is plug in some numbers and then think why you are getting GCD = 1 in each case and whether it will be true for all pair of values.
Check out Bunuel's explanation above. It's very important and you can expect to be tested on such concepts in GMAT.
I solved the above problem in the following manner. Please let me know whether that is the right approach or not.
=> x & y have no common factors other than 1 in each cases. Sufficient
=> In each of the above cases, x & y have GCF=1. Sufficient