Critical Reasoning

While Choice D is correct, negation of Choice A also leads to a requirement for reducing ash.
If all the materials separated for recycling is incenerated, then that process will add to ash.
Is Choice A neglected based on assumption that recycling will not lead to incineration?

kutlee wrote:While Choice D is correct, negation of Choice A also leads to a requirement for reducing ash.
If all the materials separated for recycling is incenerated, then that process will add to ash.
Is Choice A neglected based on assumption that recycling will not lead to incineration?

Conclusion: The AMOUNT OF ASH that is incinerated will be reduced by half.

An assumption is WHAT MUST BE TRUE for the plan to achieve its aim.
When the correct answer choice is NEGATED, the plan must fall apart.
The opposite of none is SOME.
Answer choice A, negated:
This year, SOME materials that city services could separate for recycling will be incinerated.
This negation does not invalidate the conclusion that the amount of incinerated ash will be reduced by half.
Eliminate A.

hi�I chose Choice E. Could I think in this way？

If use negation method ,this choice is The total quantity of refuse collected byShelbyville city services this year greater than that collected last year.

Does this involve a little math ? Because in certain circumstance where the quantity of refuse is greater or more than twice that last year , the conclusion can be invalidated, right ???
But, on the other hand , if there is a just minor increment, the conclusion can't be weakened.

SO choice E is not a necessary assumption.
Thanks!

GMATGuruNY wrote:

kutlee wrote:While Choice D is correct, negation of Choice A also leads to a requirement for reducing ash.
If all the materials separated for recycling is incenerated, then that process will add to ash.
Is Choice A neglected based on assumption that recycling will not lead to incineration?

Conclusion: The AMOUNT OF ASH that is incinerated will be reduced by half.

An assumption is WHAT MUST BE TRUE for the plan to achieve its aim.
When the correct answer choice is NEGATED, the plan must fall apart.
The opposite of none is SOME.
Answer choice A, negated:
This year, SOME materials that city services could separate for recycling will be incinerated.
This negation does not invalidate the conclusion that the amount of incinerated ash will be reduced by half.
Eliminate A.

notyet wrote:hi�I chose Choice E. Could I think in this way？

If use negation method ,this choice is The total quantity of refuse collected byShelbyville city services this year greater than that collected last year.

Does this involve a little math ? Because in certain circumstance where the quantity of refuse is greater or more than twice that last year , the conclusion can be invalidated, right ???
But, on the other hand , if there is a just minor increment, the conclusion can't be weakened.

SO choice E is not a necessary assumption.
Thanks!

GMATGuruNY wrote:

kutlee wrote:While Choice D is correct, negation of Choice A also leads to a requirement for reducing ash.
If all the materials separated for recycling is incenerated, then that process will add to ash.
Is Choice A neglected based on assumption that recycling will not lead to incineration?

Conclusion: The AMOUNT OF ASH that is incinerated will be reduced by half.

An assumption is WHAT MUST BE TRUE for the plan to achieve its aim.
When the correct answer choice is NEGATED, the plan must fall apart.
The opposite of none is SOME.
Answer choice A, negated:
This year, SOME materials that city services could separate for recycling will be incinerated.
This negation does not invalidate the conclusion that the amount of incinerated ash will be reduced by half.
Eliminate A.

No math required to eliminate E. The plan is to separate out enough recycling so that there will be half as many truckloads of refuse to incinerate. If there's more total refuse, they could simply separate out more recycling. What matters is the rate at which the refuse is converted to ash.

Thanks for your reply.
I understand what you mean.

But! I notice the conclusion is "to reduce the number of truckloads of refuse to be incinerated to half of last year's number.".
When the last year's number is fixed, this year ,you got way too much refuse ,the half of which still can be more than your goal.

DavidG@VeritasPrep wrote:

notyet wrote:hi�I chose Choice E. Could I think in this way？

If use negation method ,this choice is The total quantity of refuse collected byShelbyville city services this year greater than that collected last year.

Does this involve a little math ? Because in certain circumstance where the quantity of refuse is greater or more than twice that last year , the conclusion can be invalidated, right ???
But, on the other hand , if there is a just minor increment, the conclusion can't be weakened.

SO choice E is not a necessary assumption.
Thanks!

GMATGuruNY wrote:

kutlee wrote:While Choice D is correct, negation of Choice A also leads to a requirement for reducing ash.
If all the materials separated for recycling is incenerated, then that process will add to ash.
Is Choice A neglected based on assumption that recycling will not lead to incineration?

Conclusion: The AMOUNT OF ASH that is incinerated will be reduced by half.

An assumption is WHAT MUST BE TRUE for the plan to achieve its aim.
When the correct answer choice is NEGATED, the plan must fall apart.
The opposite of none is SOME.
Answer choice A, negated:
This year, SOME materials that city services could separate for recycling will be incinerated.
This negation does not invalidate the conclusion that the amount of incinerated ash will be reduced by half.
Eliminate A.

No math required to eliminate E. The plan is to separate out enough recycling so that there will be half as many truckloads of refuse to incinerate. If there's more total refuse, they could simply separate out more recycling. What matters is the rate at which the refuse is converted to ash.

Thanks for your reply.
I understand what you mean.

But! I notice the conclusion is "to reduce the number of truckloads of refuse to be incinerated to half of last year's number.".
When the last year's number is fixed, this year ,you got way too much refuse ,the half of which still can be more than your goal.

Remember: the goal is to have half as many trucks of refuse to be incinerated as there werelast year. Imagine the following scenario

Last year: 100 trucks of refuse total (all to be incinerated)

This year: 50 trucks of refuse to be incinerated

Notice that the total number of trucks this year is irrelevant. If there'd again been 100 total trucks carrying refuse, then 50 trucks would carry refuse to be incinerated and 50 would carry refuse to be recycled. If there'd been 110 total trucks carrying refuse, 50 trucks would carry refuse to be incinerated and 60 would carry refuse to be recycled. In other words, the 50 trucks carrying refuse to be incinerated is fixed. If the total increases, it just means more trucks carrying recycled material.