GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 13 Dec 2018, 14:35

### GMAT Club Daily Prep

#### 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

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

## Events & Promotions

###### Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• ### GMATbuster's Weekly GMAT Quant Quiz, Tomorrow, Saturday at 9 AM PST

December 14, 2018

December 14, 2018

09:00 AM PST

10:00 AM PST

10 Questions will be posted on the forum and we will post a reply in this Topic with a link to each question. There are prizes for the winners.
• ### The winning strategy for 700+ on the GMAT

December 13, 2018

December 13, 2018

08:00 AM PST

09:00 AM PST

What people who reach the high 700's do differently? We're going to share insights, tips and strategies from data we collected on over 50,000 students who used examPAL.

# Did at least 15 percent of the children in Springfield suffer adverse

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 51185
Did at least 15 percent of the children in Springfield suffer adverse  [#permalink]

### Show Tags

19 Sep 2016, 04:47
2
7
00:00

Difficulty:

55% (hard)

Question Stats:

58% (01:29) correct 42% (01:37) wrong based on 161 sessions

### HideShow timer Statistics

Did at least 15 percent of the children in Springfield suffer adverse effects after taking a certain vaccination?

(1) Among the Springfield children, 20 percent of the girls and more than 10 percent of the boys suffered adverse effects after taking the vaccination.

(2) Among the Springfield children, 20 percent of the boys and more than 15 percent of the girls suffered adverse effects after taking that vaccination.

_________________
CEO
Joined: 11 Sep 2015
Posts: 3237
Re: Did at least 15 percent of the children in Springfield suffer adverse  [#permalink]

### Show Tags

19 Sep 2016, 07:02
3
Top Contributor
3
Bunuel wrote:
Did at least 15 percent of the children in Springfield suffer adverse effects after taking a certain vaccination?

(1) Among the Springfield children, 20 percent of the girls and more than 10 percent of the boys suffered adverse effects after taking the vaccination.

(2) Among the Springfield children, 20 percent of the boys and more than 15 percent of the girls suffered adverse effects after taking that vaccination.

Target question: Did at least 15 percent of the children in Springfield suffer adverse effects after taking a certain vaccination?

Statement 1: Among the Springfield children, 20% of the girls and more than 10% of the boys suffered adverse effects after taking the vaccination.
This question tests an important (and often-tested) GMAT concept - weighted averages.

Let's say that 12% of the boys suffered adverse effects.
There are three possible scenarios to consider:
a) IF there were an EQUAL number of boys and girls, then the percentage of all children who suffered adverse effects would equal the average of 12% of 20%. So, the percentage of all children who suffered adverse effects would equal (20% + 12% )/2 = 16%
b) IF there were an MORE girls than boys, then the percentage of all children who suffered adverse effects would be closer to 20% than to 12%
c) IF there were an MORE boys than girls, then the percentage of all children who suffered adverse effects would be closer to 12% than to 20%

Now consider the following CONFLICTING cases
Case a: 20% of the girls suffered adverse effects, and 20% of the boys suffered adverse effects. If there are 2 girls and 2 boys, then 20% of all children suffered adverse effects.
Case b: 20% of the girls suffered adverse effects, and 11% of the boys suffered adverse effects. If there are 2 girls and 1000 boys, then the percentage of all children who suffered adverse effects will be very very close to 11%, since the boys have the bigger influence on the total percentage
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: Among the Springfield children, 20 percent of the boys and more than 15 percent of the girls suffered adverse effects after taking that vaccination.
Since both groups (boys and girls) are such that EACH suffered more than 15% , then the COMBINED population is certain to have an adverse rate that's greater than 15%
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

RELATED VIDEO

_________________

Test confidently with gmatprepnow.com

##### General Discussion
Retired Moderator
Joined: 26 Nov 2012
Posts: 591
Did at least 15 percent of the children in Springfield suffer adverse  [#permalink]

### Show Tags

19 Sep 2016, 06:05
Bunuel wrote:
Did at least 15 percent of the children in Springfield suffer adverse effects after taking a certain vaccination?

(1) Among the Springfield children, 20 percent of the girls and more than 10 percent of the boys suffered adverse effects after taking the vaccination.

(2) Among the Springfield children, 20 percent of the boys and more than 15 percent of the girls suffered adverse effects after taking that vaccination.

Stat 1: let x be for boys and y be girls

0.2(y)+ >0.1(x)...we can't say anything from this.

Stat 2: 0.2(x) + > 0.15(y)... since we have information here itself that more than 15 percent of the girls suffered adverse effects... we can say that > 15% of children suffer adverse effects when we club boys information too...I go for B.

IMO option B.
DS Forum Moderator
Joined: 21 Aug 2013
Posts: 1412
Location: India
Re: Did at least 15 percent of the children in Springfield suffer adverse  [#permalink]

### Show Tags

04 Dec 2017, 10:04
Bunuel wrote:
Did at least 15 percent of the children in Springfield suffer adverse effects after taking a certain vaccination?

(1) Among the Springfield children, 20 percent of the girls and more than 10 percent of the boys suffered adverse effects after taking the vaccination.

(2) Among the Springfield children, 20 percent of the boys and more than 15 percent of the girls suffered adverse effects after taking that vaccination.

If the total number of people is made up of X and Y (Thus total being X+Y), and we are given an attribute that is shared by a% of these X people, and b% of these y people, and we are asked what is the overall % of people (out of total X+Y) who share this attribute, then that % will always be between a and b. So overall % in these cases will be somewhere between the two. Now if value of X is more than Y, answer will be closer to a, and vice-versa. This is a concept of weighted average and can be applied in this question.

(1) We dont know how many girls are there and how many boys are there. But since this effect is present in 20% of girls and more than 10% of boys, overall percent children with this effect would lie somewhere between 10% and 20%. If the number of girls is more than boys, children affected would be more than 15%, but if number of boys is more, it could be less than 15% (we dont even know whats the exact percentage of boys affected). So Insufficient.

(2) 20% of boys affected, more than 15% of girls affected. By same concept, overall children affected would be somewhere between 20% and 15%, thus more than 15% definitely. Sufficient.

Re: Did at least 15 percent of the children in Springfield suffer adverse &nbs [#permalink] 04 Dec 2017, 10:04
Display posts from previous: Sort by