A telecommunications companys stock fell 10% last month, while a riva

Question

A telecommunications company’s stock fell 10% last month, while a rival company’s stock increased by 10%. The rival company’s stock value today is what percentage of the telecommunication company’s stock value at the beginning of last month?

(1) The rival company’s stock was valued at $42 per share at the beginning of last month.

(2) The dollar amount of the rival company’s stock increase was 90% as much as the dollar amount of the decrease in the telecommunication company’s stock.

Are You Up For the Challenge: 700 Level Questions

GMATinsight · Answer

Last month prices of stocks = a and b This month prices of stocks = 0.9a and 1.1b Question: 1.1b = (x/100)*0.9a? Question REPHRASED: x = 1.1b*100/0.9a = (1100/9)*(b/a) = ? Statement 1 : The rival company’s stock was valued at $42 per share at the beginning of last month. we need b/a while the statement gives us the value of b hence NOT SUFFICIENT Statement 2 : The dollar amount of the rival company’s stock increase was 90% as much as the dollar amount of the decrease in the telecommunication company’s stock. Increase of rival company stock = 1.1a-a = 0.1b = (90/100)*(0.1b) Now, we have b/a hence SUFFICIENT P.S. As long as we can predict that we are getting what we want from an expression, we must avoid getting in exact calculation in DS problems. It saves TIME

Answer: Option B

yashikaaggarwal · Answer

Let the telecommunications company’s stock value at the beginning of last month be x which fell 10% last month = 0.9x

And rival company’s stock at the beginning of last month is Y, which increased by 10% = 1.1Y

The rival company’s stock value today is what percentage of the telecommunication company’s stock value at the beginning of last month = 1.1y is what percentage of X

Statement 1: The rival company’s stock was valued at $42 per share at the beginning of last month.
Y = 42
Increase = 42*1.1 = 46.2
We need to know 46.2 is what percentage of X
=> 46.2*100/X 
No value of X (insufficient)

Statement 2: The dollar amount of the rival company’s stock increase was 90% as much as the dollar amount of the decrease in the telecommunication company’s stock.
Increase in rival stock = 0.1Y
Decrease in telecommunication company stock = 0.1x
0.1y = 0.9*0.1x
0.1y = 0.09x
X/y = 1.111/1 or y/x = 0.9
We want the value of 1.1y/x*100
Putting values.
1.1*y/x*100
1.1*0.9 = 0.99
(Sufficient)

Answer is B

Posted from my mobile device

GMATWhizTeam · Answer

Solution 
 Step 1: Analyse Question Stem 
 • Let us assume that the stock values of the telecommunication company and its rival were x and y (in dollars per share), respectively, at the beginning of the last month.
• Today, the stock value of the telecommunication company  = 0.9x 
 o And, the stock value of it’s rival company, today  = 1.1y  
• We need to find the value of  \frac{1.1y}{x}*100 …..Eq.(i) 
 o Or, we just need to find  \frac{y}{x}

Step 2: Analyse Statements Independently (And eliminate options) – AD/BCE 
 Statement 1:  The rival company’s stock was valued at $42 per share at the beginning of last month.
 • According to this statement,  y = 42 $
• However, we don’t know x. So, we cannot find  \frac{y}{x}  
Hence, statement 1 is NOT sufficient and we can eliminate answer Options A and D.

Statement 2:  The dollar amount of the rival company’s stock increase was 90% as much as the dollar amount of the decrease in the telecommunication company’s stock.
 • According to this statement,  0.1y =0.9*0.1*x ⟹ \frac{y}{x} = 0.9  
 o We can easily substitute the value of  \frac{y}{x}  into Eq.(i) to find the required percentage.  
Hence, statement 2 is sufficient.
Thus, the correct answer is  Option B.

vipulshahi · Answer

TC stock fell last month = 10% ; Today, the stock value of the telecommunication company =0.9x=0.9x
rival's stock increased last month = 10% ; And, the stock value of it’s rival company, today =1.1y=1.1y

1.1y = m% * 0.9x 
m=?

St1: rivals stock value, y = $42
The value of "x" we don't know ; Not Suff.

St2: 0.1*y = 0.9* 0.1 * x 
Thus we can find the value of y / x = 0.9
Sufficient

Thus, the correct answer is Option B.

HoneyLemon · Answer

Ans : B  , imo

------------------ ----------Last Month----------------------This month-------

--Telecom Stock -----------S--------------------------------0.9 S ---

--Rival Stock---------------R--------------------------------1.1 R----

Ques is (1.1 R / S ) * 100 = ?

So if we get the value of R?S.. we can get the final value .

Statement 1: The rival company’s stock was valued at $42 per share at the beginning of last month.

No info about S . so  NOT SUFFICIENT

Statement 2: The dollar amount of the rival company’s stock increase was 90% as much as the dollar amount of the decrease in the telecommunication company’s stock.

0.1R = 0.9 (0.1)S 
So we can find R/S and the final value . Hence  SUFFICIENT

So ans is B .

unraveled · Answer

A telecommunications company’s stock fell 10% last month, while a rival company’s stock increased by 10%. The rival company’s stock value today is what percentage of the telecommunication company’s stock value at the beginning of last month?

Price of Company stock at the start of month,  P_c = x 
Price of Company stock at the end of month,  P_c' = 0.9x 
Price of rival Company stock at the start of month,  P_{rc} = y 
Price of rival Company stock at the end of month,  P_{rc}' = 1.1y

\frac{P_{rc}' - P_c}{P_c} * 100 = \frac{1.1 y - x}{x} * 100  = ?
 \frac{P_{rc}'}{P_c} = \frac{1.1 y}{x} = ? 
 \frac{y}{x} = ?

(1) The rival company’s stock was valued at $42 per share at the beginning of last month.
y = 42
x = ?

INSUFFICIENT.

(2) The dollar amount of the rival company’s stock increase was 90% as much as the dollar amount of the decrease in the telecommunication company’s stock.
1.1y - y = 0.9 * (x - 0.9x)
0.1y = 0.9 * 0.1x
 \frac{y}{x} = 0.9 
 \frac{P_{rc}'}{P_c} = 1.1 * 0.9 = 0.99

SUFFICIENT.

Answer B.

sambitspm · Answer

Kindly see the attachment.
Need to find the ratio of prices of TC and rival company
B

bumpbot · Answer

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

A telecommunications companys stock fell 10% last month, while a riva

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

GMAT Data Sufficiency (DS) Questions

A telecommunications companys stock fell 10% last month, while a riva

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