Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

I am not an expert... But this is how I got to the answer...

51. According to surveys by the National Institute on Drug Abuse, about 20 percent of young adults used cocaine in 1979, doubling those reported in the 1977 survey. (A) doubling those reported in the 1977 survey -- What is those pointing to?? Replace "20 percent of young adults" in the later...and not proper (B) to double the number the 1977 survey reported -- not proper (C) twice those the 1977 survey reported (D) twice as much as those reported in the 1977 survey -- What is those (E) twice the number reported in the 1977 survey -- correct

Still, I am looking forward from the experts on their approach
_________________

This is a comparison issue; so what are being compared? A number (that is 20 percent which is a quantum and hence singular) has to be compared with some thing similar. Therefore, the other arm of the comparison should also indicate a quantum number. The spoil - sport is the ambiguous those in A,C and D. In B to double the number gives an absurd dimension that the 20 percent went on mission to double the number

Choice E succinctly compares the 20 percent with twice the number.
_________________

“Better than a thousand days of diligent study is one day with a great teacher” – a Japanese proverb. 9884544509

According to surveys by the National Institute on Drug [#permalink]

Show Tags

19 May 2012, 03:22

According to surveys by the National Institute on Drug Abuse, about 20 percent of young adults used cocaine in 1979, doubling those reported in the 1977 survey. (A) doubling those reported in the 1977 survey (B) to double the number the 1977 survey reported (C) twice those the 1977 survey reported (D) twice as much as those reported in the 1977 survey (E) twice the number reported in the 1977 survey

The comparison has to be like. As the number (or percentage) of adults is being adults is being reported in 1979, it must be compared to a number (and not to the number of adults) in 1977.

According to surveys by the National Institute on Drug Abuse, about 20 percent of young adults used cocaine in 1979, doubling those reported in the 1977 survey. (A) doubling those reported in the 1977 survey (B) to double the number the 1977 survey reported (C) twice those the 1977 survey reported (D) twice as much as those reported in the 1977 survey (E) twice the number reported in the 1977 survey

A, B and C are obviously out. Between D and E, D uses 'much' and this is used for comparing indefinite amounts e.g. too much sugar in the tea. Since we have a definite number here, it has to be E

According to surveys by the National Institute on Drug Abuse, about 20 percent of young adults used cocaine in 1979, doubling those reported in the 1977 survey. (A) doubling those reported in the 1977 survey (B) to double the number the 1977 survey reported (C) twice those the 1977 survey reported (D) twice as much as those reported in the 1977 survey (E) twice the number reported in the 1977 survey

A: doubling those reported is not right as it is trying to double those young adults... HENCE WRONG B: both segments are incomplete.. about 20% percent of young adults used cocaine in 1979 and to double the number the 1977 survey reported.. are we trying to double the number survey reported? hence WRONG C: TWICE THOSE, is 1979 twice those? WRONG D: TWICE as much as those reported.. here again 1979 is talked about hence WRONG E: here it clearly compares 20% with the twice the number... hence CORRECT

may be i am wrong in understanding, can somebody help
_________________

Regards, Harsha

Note: Give me kudos if my approach is right , else help me understand where i am missing.. I want to bell the GMAT Cat

According to surveys by the National Institute on Drug Abuse, about 20 percent of young adults used cocaine in 1979, doubling those reported in the 1977 survey.

The above red one is being compared.

(A) doubling those reported in the 1977 survey wrong comparison. 20 percent of young adults vs a number of those reported

(B) to double the number the 1977 survey reported to double, infinite form is wrong.

(C) twice those the 1977 survey reported wrong comparison. 20 percent of young adults vs a number of those reported

(D) twice as much as those reported in the 1977 survey wrong comparison. much is non-countable.

(E) twice the number reported in the 1977 survey correct.
_________________

Luck is the additional surplus on the way to one's constant effort.

Re: According to surveys by the National Institute on Drug [#permalink]

Show Tags

29 Aug 2012, 09:13

Okay , let me put a bit of math in here. If option "D" were "twice as MANY as those reported in the 1977 survey" would it be right?

I know many people up here said that here the comparison is between 20% and X%. BUT, and I may be wrong, What is 20% of 100 people? is it 20 people or just the number 20? We often say statements such as "50% of people are rich". We mean a certain number of PEOPLE are rich and not that the NUMBER is rich. If we follow the same analogy here, does it make the modified option "D" correct?

Would be glad if someone comments on this one.
_________________

According to surveys by the National Institute on Drug Abuse [#permalink]

Show Tags

10 Jul 2013, 07:17

According to surveys by the National Institute on Drug Abuse, about 20 percent of young adults used cocaine in 1979, doubling those reported in the 1977 survey. A. doubling those reported in the 1977 survey B. to double the number the 1977 survey reported C. twice those the 1977 survey reported D. twice as much as those reported in the 1977 survey E. twice the number reported in the 1977 survey

Hi All, (What I know) Twice is used for following comparison where some numbers or quantity is mentioned.

Ex: He has got 50 balls,twice as many as I have. USA has roughly twice as many people as India (does).

Similarly in the above example 20% is twice that present in 1977 Am I correct in understanding the usage of twice or any other way to find the usage.

If the options would have been

D1. twice as many as reported in the 1977 survey D2. twice as many as those reported in the 1977 survey

Is D1/D2 correct?I do understand 20% is compared to a number in 1977 which is twice.Why can't we say 20 adults are twice that present in 1977. Is much used for % ?

Apology if I have not asked the question correct way.I want to clear my understanding of twice & much.

Last edited by Zarrolou on 10 Jul 2013, 07:20, edited 2 times in total.

Re: According to surveys by the National Institute on Drug [#permalink]

Show Tags

10 Jul 2013, 22:58

(C) twice those the 1977 survey reported Why is this wrong (E) twice the number reported in the 1977 survey here the persons are compared to numbers, why is this correct

Re: According to surveys by the National Institute on Drug [#permalink]

Show Tags

10 Jul 2013, 23:36

1

This post received KUDOS

ankurgupta03 wrote:

(C) twice those the 1977 survey reported Why is this wrong (E) twice the number reported in the 1977 survey here the persons are compared to numbers, why is this correct

Some one please explain

hi ankur,

option E :==>NUMBERS ARE COMPARED TO NUMBERS AND NOT PERSON TO NUMBERS.

lets see: 20 percent of X=RESULT==>If you see..result is always a numerical value....whenever there is mathematics ...it is going to give you value. for example: if you have 100 gm protein==>if i say 20 percent of protein you will burn while running==>what does this mean=>20 gm protein you will utilise while burning===>thats a numerical value===>so takeaway is that whenever you have PERCENT OF SOMETHING===>then you should always compare to numerical thing..and not to any other thing.

moreover in option C THOSE ==>it ise referring to children so we cant compare number with children.

hope it helps
_________________

When you want to succeed as bad as you want to breathe ...then you will be successfull....

GIVE VALUE TO OFFICIAL QUESTIONS...

GMAT RCs VOCABULARY LIST: http://gmatclub.com/forum/vocabulary-list-for-gmat-reading-comprehension-155228.html learn AWA writing techniques while watching video : http://www.gmatprepnow.com/module/gmat-analytical-writing-assessment : http://www.youtube.com/watch?v=APt9ITygGss

According to surveys by the National Institute on Drug Abuse, about 20 percent of young adults used cocaine in 1979, doubling those reported in the 1977 survey.

(A) doubling those reported in the 1977 survey (B) to double the number the 1977 survey reported (C) twice those the 1977 survey reported (D) twice as much as those reported in the 1977 survey (E) twice the number reported in the 1977 survey

Please find my understanding and let me know my mistakes.

Lets say there are 100 adults in 1977 and 1979. About 20% is 20 in 1979 and it must be 10 in 1977. if I re frame the question :

(D)about 20 adults used cocaine in 1979,twice 10 adults reported in 1977 survey. (E)about 20 adults used cocaine in 1979,twice 10 reported in 1977 survey.

So whyn't D be a better answer.Because 20 adults is twice that of 10 adults reported in survey.

Last edited by Narenn on 20 Jul 2013, 07:01, edited 1 time in total.

Merging Similar Topics Refer to the Brian's post in the similar thread http://gmatclub.com/forum/according-to-surveys-by-the-national-institute-on-drug-19660.html#p820081

Happy New Year everyone! Before I get started on this post, and well, restarted on this blog in general, I wanted to mention something. For the past several months...

It’s quickly approaching two years since I last wrote anything on this blog. A lot has happened since then. When I last posted, I had just gotten back from...

Happy 2017! Here is another update, 7 months later. With this pace I might add only one more post before the end of the GSB! However, I promised that...