visible burglar alarms

[mbernstein04]

why must the conclusion be only some visible burglar alarms make the home less likely for intrustion?

[ManhattanPrepLSAT1]

I'd love to help but not sure which question you're looking at. Can you post the whole P and (A) parts as well as both the correct conclusion (which is what I think you already posted) and the incorrect conclusion.

That way I can look at the same question you're looking at!

[storm_cyclones_]

I also have the same doubt with this question.

P: Highly visible burglar alarms reduce the likelihood that a home will be robbed.

A: (If something makes a home less likely to be robbed, that thing is a useful device.)

Incorrect Conclusion: All visible burglar alarms are useful devices.

Correct Conclusion (aka correct answer): Some highly visible burglar alarms are useful devices.

Why is the Incorrect Conclusion incorrect? The premise doesn't specify to us that only some alarms reduce the likelihood that a home will be robbed. Therefore, can't we deduce that alarms are useful devices?

[noah]

P: Highly visible burglar alarms reduce the likelihood that a home will be robbed.

A: (If something makes a home less likely to be robbed, that thing is a useful device.)

Incorrect Conclusion: All visible burglar alarms are useful devices.

We can conclude that highly visible alarms are useful, but not ALL of them.

Make sense?

[storm_cyclones_]

Yes, thank you!