LR Weaken Question help - PT22.S2.Q8 - Pear trees & insects Forum

[ComatoseClown]

I really think choice D is much better than A. (I'm not seeing how A is the right one.)

D says that some insects species that are water breeders (i.e. they reproduce and create offspring in water), and that the reservoirs and marshlands have been shrinking rapidly over the past three years. How does this have any relation to whether insects have been limited by pear pesticides? And moreover, how can the decline of these bodies of water be caused by the insects themselves? Insects can't cause bodies of water to shrink! If anything it's the other way around -- (for instance if it's contaminated water, then the insects die due to the contaminated water).

On the other hand, A seems to definitely weaken the argument! Because if the amount of mature peer trees has declined steadily over the past 8 years, it means that the new pesticide is NOT effective...contrary to the official's conclusion.

Could someone please explain why D definitely weakens the official's argument?

[WhoIsDonDraper]

(A) Doesn't weaken it actually at all. Even if the total number of trees has declined, the proportion of pears lost to insects would stay the same. Here is an example.

Number of trees: 100
Amount of fruit produced: 100 pears
Proportion lost to insects: 10% or 10 pears

Number of trees: 50
Amount of fruit produced:50 pears
Proportion lost to insects: 10% or 5 pears

Even if the number of trees declines it has nothing to do with the supposedly causal relationship that this new pesticide is more effective. You made the mistake of comparing total numbers with percentages. The LR Bible does a pretty good job of outlining the conclusions you can draw when thinking about totals and proportions.

[WhoIsDonDraper]

Oh and about (D): if the bugs are less likely to breed, then they will not likely be eating as many pears as before, since there is probably less of them to mess with the trees of these extremely annoyed peach farmers. So that would weaken the causal strength of the official and provide another explanation to why less peaches are being lost, not because of the pesticide but because the insects themselves aren't breeding as much as they used to.

[Blessedassurance]

I really think choice D is much better than A. (I'm not seeing how A is the right one.)

D says that some insects species that are water breeders (i.e. they reproduce and create offspring in water), and that the reservoirs and marshlands have been shrinking rapidly over the past three years. How does this have any relation to whether insects have been limited by pear pesticides? And moreover, how can the decline of these bodies of water be caused by the insects themselves? Insects can't cause bodies of water to shrink! If anything it's the other way around -- (for instance if it's contaminated water, then the insects die due to the contaminated water).

On the other hand, A seems to definitely weaken the argument! Because if the amount of mature peer trees has declined steadily over the past 8 years, it means that the new pesticide is NOT effective...contrary to the official's conclusion.

Could someone please explain why D definitely weakens the official's argument?

The new pesticide was applied for three years. The proportion of pears lost was significantly less than it had been during the previous three years. The official concluded etc etc.

Answer A says mature pears have been declining over a period of eight years. It means they had been declining both in the three years preceding the usage of the old pesticide and the subsequent three years in which the new pesticide was used. As such the decline had occured in both periods. Notice that answer D restricts the decline in reservoirs and marshlands to the past three years which coincides with the period for the new pesticide.

Also, what the above poster said.