A company plans to develop a prototype weeding machine that uses cutting blades with optical sensors and microprocessors that distinguish weeds from crop plants by differences in shade of color. The inventor of the machine claims that it will reduce labor costs by virtually eliminating the need for manual weeding.

Which of the following is a consideration in favor of the company’s implementing its plan to develop the prototype?

A. There is a considerable degree of variation in shade of color between weeds of different species.
B. The shade of color of some plants tends to change appreciably over the course of their growing season.
C. When crops are weeded manually, overall size and leaf shape are taken into account in distinguishing crop plants from weeds.
D. Selection and genetic manipulation allow plants of virtually any species to be economically bred to have a distinctive shade of color without altering their other characteristics.
E. Farm laborers who are responsible for the manual weeding of crops carry out other agricultural duties at times in the growing season when extensive weeding is not necessary.

Source: Retired Test papers

Conclusion: The new machine will reduce the manual weeding.
Why?
because it will distinguish between weeds and crop plants by the color.
So the company will prefer this machine only if we strength this argument.
lets deal with each option.

A. if there is a considerable variation within the weeds itself than the machine will cut some weeds as well..which it should'nt.. so this Weakens

B.if the plants too change there color than it might be possible that some plants are left over(i.e aren't cut). so this weakens

C. this one favors manual weeding..Not what we require

D. if bred correctly, plants will have a specific shade of color and rest will remain unchange which is in line with the underlying assumption.. probable YES.

E. talks about farm labor activities..seems Out of Scope.

hence D


C.

I agree, dhingra. swapna, did you have a specific question about this problem? Also, can you tell me more about this source . . . is this an official GMAT problem?

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Jamie Nelson
ManhattanGMAT Instructor

I could not understand the difference between B and D.
"B" says that some plants change color
"D" says plants can have different color depending on selection & gene manipulation that essentially means plants can have different color.
If B is weakening the plan then why not D?

if this problem comes from old GMAT paper tests, we will have to delete the question according to our forum rules. please provide clarification of the source before we can discuss this problem further..

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Tim Sanders
Manhattan GMAT Instructor

b) the fact that some plants' color might change during their growth, shows that weed and plants might also change their color. This means the machine can leave some weeds or crop some plants. So, it proves machine is ineffective.

d) Since plants can be bred to change colors, only desired plants will be bred so. Not weed. So machine can crop all weeds that don't have the particular color of the desired plant.

Hope this clears it up.

Thanks,
Kris

nope, sorry, that does NOTHING to clarify the source of the problem..

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Tim Sanders
Manhattan GMAT Instructor