@Edbnapa I'm pretty sure the lesson was on "or" (not and) being equivalent to and/or. This interpretation was only possible sometimes. The interpretation also depends on the context of the sentence.

@DeborahJimenez I think its helpful if you follow the translation rule which says to 1. take either of the two claims/ideas. 2. negate it. 3. make that the sufficient condition (meaning the other has to be the necessary condition. and then put into lawgic form.

I also think its helpful if you convert into lawgic for both phrases/ideas having a situation where each idea is the sufficient condition, leaving you with 2 lawgic "sentences". This lets you interpret it however makes the most sense to you.

The Kumar example was the most confusing but I think I understand it now.

Original sentence:

Students are cited as "late" only if they arrive more than five minutes past the last ring of the homeroom bell.

Lets say

A = late

B = 5+ minutes after homeroom bell

Another way of thinking about this is that "late" is the subset within the 5+ superset.

so in lawgic:

late --> 5+

/5+ --> /late

Now: Kumar arrived 17 min after the last ring of the homeroom bell.

So Kumar has membership in superset B (5+ min after homeroom bell), but that does not mean that he HAS to have membership in subset A (late). In the visual example, he would be within the 5+ superset circle, but outside of the "late" subset circle.

In practice, this might be because the teacher might have decided not to mark Kumar as late, or forgotten to mark him as late.

I might be wrong and feel free to respond, but this is how I understood it.

The Disney one exhausts other options, making it the strongest. The tiger one has the strongest support (assumed true) as a pet that is aggressive and can cause serious injury would not be suitable as a pet. The Trash Bin is the weakest because there is room for doubt. There is no conclusive evidence, only circumstantial pointing towards the cat, but maybe he ate the salmon after the trash bin had already fallen from another cause? or maybe Mr. Fat Cat had eaten something else other than the salmon? There is lots of doubt on the Trash Bin argument whereas Disney leaves no room for doubt.