Can anyone explain these logic questions to me?

Question

I didn't do bad on this logical quiz, but I got these two wrong and I just have no idea how they work. Anyone got any ideas.

1. It is true that (Karen has a mobile phone or Karen has broadband internet).

It is true that (Karen has a mobile phone).

a. Karen has broadband internet is true.

b. Karen has boradband internet is false.

c. The given conditions are inconsistant.

d. No one of the above alternatives is valid.

2. It is false that (Karen has a mobile phone or Karen has broadband internet).

It is true that (Karen has broadband internet).

a. Karen has a mobile phone is true.

b. Karen has a mobile phone is false.

c. The given conditions are inconsistant.

d. No one of the alternatives is valid.

So.. the answers are d and c respecitively.

Anyone wanna give it a shot at explaining why?

Answer 1

1. A and B contradict eachother. C points this out, and D says that more than 1 of the above are correct. That means that either 2 or 3 of the statements are correct. But, as C already pointed out, A or B is lying. Only 3 of the statements are truthful.

But D has told the truth, so it's the correct answer, using A,C,D, or B,C,D.

2. A and B again contradict eachother. Again, C points this out. D says that only 1 of the above statements is correct, so the answer has to be A, B, or C.

Since C points out that A and B are lying, C is the correct answer, using C and D.

Answer 2

I could be wrong, but here's how I'd do it. I'd use Venn diagrams.

Draw 2 intersecting circles labeled M and B for mobile phone and broadband respectively.

1)  Here's the Venn diagram for the first one.

http://i36.tinypic.com/33xk26a.jpg

The first condition is represented by the total shaded region (red and black). The second condition is represented by the red. So there is overlap, which rules out C. But the red region may or may not include the intersection. So there is not enough information to decide whether it's A or B. Both could be correct, but there is no way to tell. So D.

2) Here's the Venn diagram for the second.

http://i38.tinypic.com/2exokl0.jpg

The dark region represents the first condition while the red region represents the second. There is no overlap, which means there is no way both conditions can be correct at the same time. C.

Answer 3

D and D.