DS4

Expert replies

Previous Topic Next Topic

kamalakarthi: Senior | Next Rank: 100 Posts; Posts: 80; Joined: Mon Jan 31, 2011 10:08 pmFollowed by: 2 members

by kamalakarthi » Fri Oct 17, 2014 12:30 pm

Attachments

Like this post

Source: Beat The GMAT — Data Sufficiency | Fri Oct 17, 2014 12:30 pm

j_shreyans: Legendary Member; Posts: 510; Joined: Thu Aug 07, 2014 2:24 amFollowed by: 5 members; Thanked: 3 times

by j_shreyans » Sat Oct 18, 2014 4:01 am

Hi ,

Can you pls tell the OA?

IMOD

Like this post

GMAT/MBA Expert

[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members; Location: Palo Alto, CA; Thanked: 2867 times; GMAT Score:800

by [email protected] » Sat Oct 18, 2014 8:28 pm

Hi kamalakarthi,

This DS question is essentially just a wordy algebra question. Properly translating the language in the main prompt into "math" will make the rest of the work really easy to do.

We're told that an investor owns some shares of stock, 30% of those total shares are of Stock X and 1/7 or the REMAINING shares are of Stock Y. Before doing anything else, I'm going to translate all of this into algebra:

T = Total shares owned
.3T = number of shares of Stock X

Now, to figure out the number of shares of Stock Y, we need to take the REMAINING shares (in this case, .7T shares) and multiply by 1/7...
.7T(1/7) = (7/10)(T)(1/7) = T/10 = .1T

.1T = number of shares of Stock Y

The question asks for the number of shares of Stock X, so it's asking for the value of .3T (in other words, if you can figure out the value of T, then you can answer the question).

Fact 1: The investor owns 100 shares of Stock Y

This means that .1T = 100.
We CAN solve for T and there is just one answer (and we can save time since we don't have to do the work to see that there's just one answer).
Fact 1 is SUFFICIENT

Fact 2: The investor owns 200 MORE shares of Stock X than Stock Y.

We can translate this into an equation:

.3T = .1T + 200
.2T = 200

Again, we CAN solve for T and there is just one answer.
Fact 2 is SUFFICIENT

Final Answer: D

GMAT assassins aren't born, they're made,
Rich

Contact Rich at [email protected]

Like this post

GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members; Location: New York, NY; Thanked: 13060 times; GMAT Score:790

by GMATGuruNY » Sun Oct 19, 2014 2:04 am

Of the shares of stock owned by a certain investor, 30 percent are shares of Company X stock and 1/7 of the remaining shares are shares of Company Y stock. How many shares of Company X stock does the investor own?

(1) The investor owns 100 shares of Company Y stock.
(2) The investor owns 200 more shares of Company X stock than of Company Y stock.

Alternate approach:
To determine the ratio of X and Y, plug in a value for the total number of shares.

Since the problem features two fractions -- 30% = 3/10 and 1/7 -- the total number of shares should be a value divisible by both 10 and 7.
Let the total number of shares = 70.
Since 30% of the shares are of Stock X, X = (3/10)(70) = 21.
Remaning shares = 70-21 = 49.
Since 1/7 of the remaining shares are of Stock Y, Y = (1/7)(49) = 7.
Thus:
X:Y = 21:7 = 3:1.

Statement 1: The investor owns 100 shares of Company Y stock
Since X:Y = 3:1 = 300:100, X=300 and Y=100.
SUFFICIENT.

Statement 2: The investor owns 200 more shares of Company X stock than of Company Y stock
Statement 2 implies the same values as Statement 1:
X=300 and Y=100, with the result that X-Y = 300-100 = 200.
SUFFICIENT.

The correct answer is D.

Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3

Like this post

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Sun Oct 19, 2014 12:20 pm

Of the shares of stock owned by a certain investor, 30 percent are shares of Company X stock and 1/7 of the remaining shares are shares of Company Y stock. How many shares of Company X stock does the investor own?

(1) The investor owns 100 shares of Company Y stock.
(2) The investor owns 200 more shares of Company X stock than of Company Y stock.

Target question: What is the value of n?

Given - part a: Of the shares of stock owned by a certain investor, 30 percent are shares of Company X stock ..
If 30% of the shares are Company X, then 70% of the shares are NOT in Company X

Given - part b: ... and 1/7 of the remaining shares are shares of Company Y stock
1/7 of 70% = 10%, so 10% of the shares are in Company Y

Statement 1: The investor owns 100 shares of Company Y stock.
If 30% of the shares are Company X and 10% of the shares are in Company Y, then there are 3 TIMES as many shares in Company X as in Company Y.
(3)(100) = 300, so there are 300 shares in Company X.
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: The investor owns 200 more shares of Company X stock than of Company Y stock.
So, (# of Company X shares) - (# of Company Y shares) = 200
Let T = total number of shares
So, (30% of T) - (10% of T) = 200
Rewrite as 0.3T - 0.1T = 200
Simplify: 0.2T = 200
Solve: T = 1000
So, there are 1000 shares altogether.
30% of the shares are in Company X, and 30% of 1000 = 300
So there are 300 shares in Company X.
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer = D

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review