Q15 - To reduce mosquito population

[Jacqmarie]

Why is A incorrect? Is it because of the word "most"?

[sumukh09]

Why is A incorrect? Is it because of the word "most"?

A is incorrect because it doesn't explain how the planting of trees had the opposite effect of the intended effect. The intended effect was to reduce the mosquito population and the opposite effect occurred, ie) the mosquito population got larger. A tells us that most of the bird species did not eat mosquitoes, but that doesn't help explain how the population of mosquitoes got larger - it would only explain why the population of mosquitoes remained constant.

C, however, helps explain the paradox -- the birds ate more insects that prey on mosquitoes than the mosquitoes themselves. If they ate more insects that prey on mosquitoes, then it's no wonder the population of mosquitoes grew. Before the planting of the trees, the insects that preyed on mosquitoes helped reduce the mosquito population, but after the trees were planted, the birds ate so many of the insects that more mosquitoes than normal survived. Hope this helps

[tommywallach]

Hey Guys,

Great answer from Sumukh here. That's absolutely right. We need to know why mosquitos would have increased.

Another thing that might help is to remember that we already read "the birds ate many mosquitos." So even if (A) were true, we'd still know that birds ate many mosquitos. This means mosquitos still should have gone down, even if most of the birds that came didn't eat mosquitos.

Hope that helps!

-t

[agutman]

PT69, S1, Q15(Explain the Result)

For this question type, we should start by figuring out what one would expect to happen, and compare that to what actually happened. In this case trees were planted to reduce the mosquito population. Why would trees reduce the mosquito population? OK, their fruit attracts birds, and birds eat mosquitos. We would therefore expect the mosquito population to be reduced as a result. What happened instead? The very opposite! This implies that in fact the mosquito population increased. Hmmm, very curious. The more genuine your puzzlement is, the better prepared you will be for the answer choices. Imagine how you’ll be telling this puzzling anecdote to your friends tonight, and as you go into the answer choices look for something that would make a good punch line for your tale.

(A) does this explain why the mosquito population increased rather than decreased? Not even close! It would only explain why it didn’t decrease as much as one may have hoped.

(B) is almost identical to (A), and wrong for the same reason.

(D) this makes the anecdote even more surprising than it already was! Now we have yet another reason to expect the mosquito population to be reduced... Why on earth did it end up increasing?

(E) is very tempting because it’s so vague. If you overthink this one a little, you might think that perhaps we’re in that part of the cycle where the mosquito population should increase, and thanks to the birds it increased by less than it would otherwise. But this requires making assumptions about the duration and phases of this cycle, so there is probably a better answer waiting for us in one of the other answer choices.

That leaves (C), which tells us that the birds did more harm than good. This would be a great punch line for your anecdote, when you tell it to your friends tonight. They’ll go ohhhhhhh and will thank you for an entertaining tale.

So (C) is correct.

[snoopy]

I eliminated C because I thought 'doesn't tell us that insects ate more or birds ate more' which made me think "how do you know the mosquito population increased because of the fewer insects leftover to eat mosquitoes?"

What's wrong with this thinking? I can see C being the right answer, but I still have that doubt.

edit: C is not a bullet proof explanation, but it at least provides an explanation as to why the planting of trees produced an opposite effect