Q15 - Any good garden compost

[hongruimao]

why is D not correct?

If we assume that the best compost is also good compost, we have " best compost ---> suitable for soil drainage and fertility".

Since ""Not sufficiently decomposed ------> Not suitable for soil drainage and fertility", we have "suitable for soil drainage and fertility ------> sufficiently decomposed".

Hence, "best compost ----> suitable for soil drainage and fertility ---->sufficiently decomposed".

So, why is D wrong?

Is it because "sufficiently decomposed" does not equal "completely decomposed?

Thanks.

[fmuirhea]

I believe you have it exactly right - sufficient decomposition is not necessarily synonymous with complete decomposition.

(E), on the other hand, is correct because of the conditions* in the stimulus:

good compost --> can use for drainage/fertility
strong ammonia smell --> cannot use for drainage/fertility --> not good compost

(E) tries to throw you off with that bit about the compost being dark brown (since that is one characteristic of the best compost, which, as you said, would certainly qualify as good and thus suitable for drainage/fertility use), but ultimately you're just following the conditional chain* starting at "ammonia" and ending up at "not good."




*I think the reason the stem is MSS instead of MBT hinges on the word "should," which doesn't strictly let you set up a condition, but it's okay to fudge it for the purposes of this question. Just because you shouldn't do something, doesn't mean that you can't do it - hence, linking "strong ammonia smell" to "cannot use..." is slightly incorrect. You could use compost that smells of ammonia if you wanted, but the results would probably be bad, so it's generally not advised. If any Manhattan pros could weigh in on whether this distinction is important/explains the question stem, I'd appreciate it!

[tommywallach]

Hey All,

Great conversation here. As a starting point, recognize that this is an INFERENCE question, so they allow certain levels of jumps to be made, but not others.

For example, you can't jump from

Tommy has a car

to

Tommy likes cars

But you can jump from:

When Tommy leaves early, it gives him the opportunity to go fishing

to

Tommy occasionally goes fishing

That's the equivalent of your question about "should". If they say you shouldn't do something, it's fair to assume the most logical reason (i.e. the compost is bad). Whether you like it or not, that's the reality! So let's keep those rules in mind as we go through the answers:

(A) No connection was ever drawn between the percentage of organic matter and how much it was decomposed. These do not inform each other.

(B) The passage says that the best compost is 40-60 percent organic and dark brown, but that doesn't mean any other percentage/color will be HURTFUL. Like (a), this one tries to connect up the two separate issues, color/percent and decomposition.

(C) Though we know that these two qualities (50 percent organic and good decomposition) make for good compost, we don't know about OTHER qualities that could ruin it. For example, we could have compost that's 50% organic and sufficiently decomposed, but the other 50% is plastic, or on fire! That wouldn't be good!

(D) As you've been discussing, the passage never says it should be COMPLETELY decomposed, only sufficiently. For all we know, TOTAL decomposition is actually bad! Also, we don't know the spectrum of decomposition versus goodness. It could be that perfect (best) compost, the decomposition is RIGHT at the line of sufficiency.

(E) Correct! The passage goes out of its way to say that strong ammonia smell alone is a reason not to use compost, so this will fly.

Hope that helps!

-t

[ptewarie]

Just to chime in- Remember that this is a simple formal logic inference question. Whenever that is the case, look for "definite" statements(any, all, always, must). These are usually going to be tested.

Sentence 1:

Original:

If GOOD garden compost-> may be used for soil drainage and fertilitity

Contrapositive:

if it cannot not be used for soil drainage and fertility-> NOT good garden compost

Sentence 2:
60 percent organic AND dark brown is BEST
(note that both together are sufficient, not one alone)

Sentence 3:

Strong ammonia smell-> Not be used for Drainage and Fertility

Now, note that the necessary portion of that sentence is the sufficient portion of the contrapositive of sentence 1. We can thus join together:

Strong Ammonia smell-> not used drainage and fertility-> not good garden compost.


Answer choices:

A. we dont have enough information to conclude this. All we know is that best compost is btw 40-60 percent AND is dark brown. This one probably is not the best compost, but we dont know if its sufficienty decomposed.

B. out of scope. no explanation needed

C. This one migh be tricky, but it uses sufficient conditions that are part of two formal logic statements(sentence 2 and 3).
Remember than in sentence 2, in order to be the best it must be BOTH dark brown AND between 40-60 percent organic matter. So this one is immediately ruled out.

D. "completely composed" is different than "not sufficiently decomposed"

E. Hits it on the nail. WHY?
Because it is An EXACT match for sentence 3.

Dark brown in color( ok, we don't need this) AND strong ammonia smell-> not good compost

Remember:
1. Just because A is sufficient to trigger B, it doesnt mean that
A and C cannot be together sufficient to trigger B.

[BensonC202]

Just my humble 2 cents share here.

GG -> drainage + fertility = A -> X + Y

Best -> 40-60% + db = B -> ㄅ ＋ ㄆ

( People saying it should be if 40% - 60% and dark brown color, then it must be best; however, I disagree with the interpretation for that in order for the compost " to be the best ", it must be embraced by 2 factors - 1. 40% - 60% organic matter + dark brown. I might be wrong; however, if you believe that you have better explanation, please tell me why I am wrong. )

Because ㄉ( smell ) -> not sufficient decomposed = ㄉ -> ~ SD

Compose / strong smell should not be used for drainage + fertility = C/ㄉ -> ~X + ~Y

If the soil is the best, then the best soil must be the good soil. So, by connecting all the logic chain, it could be :

{ B -> (ㄅ ＋ㄆ ) } -> { A -> ( X + Y ) -> ~ C -> ( ㄉ -> SD )

A. ~ ㄆ -> ~ SD / Mistaken Negate

B. { ～ㄅ ＋ ～ㄆ } -> ( less X + less Y ) / Mistaken Negate

C. { ㄆ ＋ SD } -> A / Mistaken Reverse

D. B -> complete decomposed

* To be sufficiently decomposed means that all the factor to initiate the decomposition process are well presented; however, it does not necessary mean that " the whole decomposition must be completed )

E. { ㄅ ＋ ㄉ } -> ~ A

* ( ㄉ -> SD ) -> { ( ~X or ~ Y or ~X + ~ Y ) -> ~ A } = ㄉ -> ~ A - Correct answer.