In a clinical trial of a new drug to treat a certain condition, 60% of

Question

In a clinical trial of a new drug to treat a certain condition, 60% of the participants were given the new drug and the rest were given a placebo. Of the participants who were given the new drug, 2/3 showed improvement. Overall, 70% of the participants showed improvement.

Select from each drop-down menu the option that creates the most accurate statement based on the information provided.

The number of participants who were given the new drug and showed improvement was "X" times the number who were given the drug and did not show improvement and "Y" times the number who were not given the new drug and did not show improvement.

Kinshook · Accepted Answer

Hi  Mike20201

New drug  Placebo  Total  
  Improvement  (2/3)*60%=40%  70%-40%=30%  70%  
  No improvement  60%-40%=20%  40%-30%=10%  30%  
  Total  60%  100%-60%=40%  100%

The number of participants who were given the new drug and showed improvement = 40%
The number of participants who were given the drug and did not show improvement = 20%
X = 40%/20% = 2

The number of participants who were given the new drug and showed improvement = 40%
The number of participants who were not given the new drug and did not show improvement = 10%
Y = 40%/10% = 4

(X,Y) = (2,4)

AndrewN · Answer

Hello,  Mike20201 . With IR questions, you have to be absolutely  certain  that you are reading the question correctly, or the section will be a nightmare. In this question, if you find that an algebraic approach eludes you, you can easily break down the percentages by choosing an arbitrary number such as 100 (since  percent  literally means  for each one hundred ) and counting up participants that would fall into each category.

Fact #1 : 60% of the participants were given the new drug
Translation: 60 participants were given the new drug
Deduction: 40 participants were NOT given the new drug (those who were given a placebo instead)

Fact #2 : Of the participants who were given the new drug, 2/3 showed improvement
Translation: Of the 60 participants given the new drug, 2/3, or 40 of them, showed improvement
Math: 
 \frac{2}{3}*60=40

Fact #3 : Overall, 70% of the participants showed improvement
Translation: Overall, 70 out of 100 participants showed improvement
Deduction: 30 of the 40 participants from the placebo group showed improvement
Math (40 from the drug group and some unknown  P  from the placebo group): 
 40+P=70

P=30

Now, we are ready to tackle the question. We have no punctuation to lean on for a natural pause to stop and process, but we do have the conjunction  and  before the "Y" part, so we can stop there and process the first half before jumping across the connector.

Question, Part 1 : The number of participants who were given the new drug and showed improvement was "X" times the number who were given the drug and did not show improvement
Translation: The 40 participants who were given the new drug AND showed improvement was _____ times the 20 who were given the new drug AND did NOT show improvement
 X = 2

Question, Part 2 :   "Y" times the number who were not given the new drug and did not show improvement
Translation: The 40 participants who were given the new drug AND showed improvement was _____ times the 10 who were NOT given the new drug and did NOT show improvement
 Y = 4

The answer should be X = 2, Y = 4.   The takeaway is that it is fine to take a little time to process a bit of information at a time as you encounter it, rather than attempting to put everything together all at once. You will definitely increase your accuracy on IR questions, and believe it or not, you will probably spend  less  time solving the question, since you will no longer need to bounce around to different parts of the screen to make sense of the given information.

I hope that helps. Good luck with your studies.

- Andrew

CrackverbalGMAT · Answer

Let me break down this question in a way that will help you tackle similar problems in the future.
First, choose 300 as the total - it's not random! When dealing with both percentages and fractions, we want a number that works nicely with the fraction (2/3).

So,
-Total: 300 participants
-Drug Group (60%): 180 people

Improved (2/3): 120 people 👍
Didn't improve (1/3): 60 people 👎

-Total improved (70%): 210 people

From drug:  120 people
 Must be from placebo:  90 people
-Placebo didn't improve: 30 people

Hence,
x = 120:60 = 2:1 (Drug improved : Drug not improved). In other words 120 is 2 times(x) 60.
y = 120:30 = 4:1 (Drug improved : Placebo not improved). In other words 120 is 4 times(y) 30.

GMAT Tip 
Always look for numbers that make your fractions play nice! In GMAT, if you see 2/3 or similar fractions, try multiples of 3 first. It'll save you from decimal headaches!
Hope this helps!

bumpbot · Answer

Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.

In a clinical trial of a new drug to treat a certain condition, 60% of

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

	New drug	Placebo	Total
Improvement	(2/3)*60%=40%	70%-40%=30%	70%
No improvement	60%-40%=20%	40%-30%=10%	30%
Total	60%	100%-60%=40%	100%

GMAT Two-part Analysis (TPA) Questions

In a clinical trial of a new drug to treat a certain condition, 60% of

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards