- Tue Oct 14, 2014 3:41 pm
#17070
Hi JK,
Thanks for the question. Your inferences are both correct.
For question 21, there is no single inference -- but several smaller ones which help eliminate the wrong choices. The way to rule out answer choice C (as you mention being down to B & C) can partially be visualized:
factories: F G H J K
year 1 V W
2 W Z
3 W
Remember that each model must show up in each year, and that Z can only show up once per year. The challenge here is that there's then no way to have X in year 1, because if X shows up in year 1 for H, J or K, that results in Z showing up twice in year 2, violating the last rule. That lends us an inference, in year 1, X will show up just once, be followed by Z just once in year 2. Therefore factory G can not have W in year 1 and Z in year 2.
You can also notice that the same will be true with X in year 2 -- Z will need to follow it in year 3 in the same factory, and nowhere else. Only in year 3, where X doesn't have to be followed by anything, will we not have to place Z just after it in the same factory.
This same combined inference will solve question 22 for you -- you know that because X must be followed by Z when it shows up in year 1 and 2, X can only show up once in those two years. That corresponds to answer choice B, which is the correct answer.
Hope this helps!
Beth