E is better only because of parallism: social and economical. Otherwise I prefer A.

i guess its same but "they do" is not required or unnecessary.

OA is D.

Q41 - OG12:
Verb form; Logical predication
Th is sentence explains a hypothetical situation and therefore calls for a conditional—or contraryto- fact—construction, because in order to more accurately predict population, demographers would have to know more than they presently
know. A present-tense verb is required to describe the current state of demographers’ knowledge, and the comparison made by the sentence must be
between current and conditional knowledge, not between knowledge and time of knowing (now). A Wrong comparison—between knowledge and time (now); conditional verb is needed. B Conditional verb is needed; economical is the
wrong adjective. C Economical is the wrong adjective. D Correct. Conditional knowledge, indicated by would have to know, is correctly compared
to current knowledge. E Wrong comparison—between what demographers need to know and now.

The correct answer is D.
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I will choose D

social and economic --> economic means related to finance ---> intended meaning

economical -thrifty ---> changes the meaning of the sentence --> making the fertility sound economical

A is clear OUT

D is left.
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Hey Noburu,

Just to weigh in real quickly, we don't want "efficient" here. We want "economic", meaning "related to the economy" (economy meaning "wealth and resources" of a region or country). We want to know how economic (money-related) factors relate to fertility, etc.

-t
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To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social and economical
C. would have to know a great deal more than they do now about the social and economical
D. would have to know a great deal more than they do now about the social and economic
E. would have to know a great deal more than now about the social and economical

E had written wrong it is not "economical". In the original exam,gmatprep 2, it is written "economic".

so i picked up E why it is not true.

I chose E can anyone explain it pls?

To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social and economical
C. would have to know a great deal more than they do now about the social and economical
D. would have to know a great deal more than they do now about the social and economic
E. would have to know a great deal more than now about the social and economic

it is the right question.
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"Than they do now" is necessary because it clarifies that comparison is between demographer's current knowledge of social and economic determinants and future knowledge. Hence. I will pick D

Don't u think that "more accurate" and "accurate" are both conditional??
In both scenarios , It is a condition to achieve something..Can you give some more examples?