my logic problems with 2 qs

[kirilrez]

The problems are attached below:





The first question bothers me the most - I chose the correct answer at first, but then changed to the incorrect answer.
First, I thought that if Jack is not good at math, then he is not good at math and therefore not an engineer and ergo an architect according to the first condition.

But, then I thought that this might be reversed logic, because I'm using the necessary part of the second statement with the sufficient part of the first one. It just felt wrong.

This led me to the wrong answer.

When I look at the question from a different prospective now I see that my response was reverse logic of the second condition.

In the end my real question is how would you have approached this question efficiently and avoided my error.

For the second question I think I see now why I should be able to infer the correct answer - if 60% of people live within 10 miles from the store, so a part of them, the 40% also live that distance from the store. But, the "more" bothers me - where does it come from?

I was just confused and chose the other option on a gut feeling.

Do the two group overlap?
I don't think so, because you either live within 5 miles of the store or 10 miles from it.
The prompt doesn't say "more" than x miles from the store..

[timmydoeslsat]

If you could please post a larger image of the first problem, I will be able to comment. As of right now, it is simply too small for me to read.

For the second problem, you are correct in the assessment that I have read. The "more" issue is simply saying that if you do not live within 10 miles, then you necessarily live 10 miles or more away. If you live, for instance, 2,000 miles away, you are indeed in this 10 miles or more group, that 40%.

We had 2 statements:

1) 40% live within 5.
2) 60% live within 10.

Those two groups necessarily overlap. If you are within 5, you are necessarily within 10.

We can infer, as this answer choice states, that 40% are ~within 10, that is, they are 10 or more.

We can also infer, from statement 1, that 60% are ~within 5, that is, they are 5 or more.

[kirilrez]

ok cool-

[timmydoeslsat]

ok cool-

OK, thanks for the bigger image.

This is setting up a true dichotomy/binary choice situation.

E or A, not both.

We know that: E ---> GM

I look at the two answer choices:

1) If Jack is ~GM, he is an A.

Absolutely we can infer this. This is the contrapositive. We go from ~GM ---> ~E, which means he is an A. He has to be one of those those two, E or A. Since he is not an E, he must be an A.

2) If Jack is GM, he is ~A.

We cannot infer this. We know that being GM is a requirement of being an E. It may also be a requirement of A, we do not know.

Analogy:

You are either a tall human being or not a tall human being, but not both.

If you are tall, you breathe oxygen.

So, if I know someone breathes oxygen, I know nothing. While it is true I have met a necessary condition of being tall, I know that meeting a requirement does not let us infer we are indeed tall.