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A telecommunications company’s stock fell 10% last month, while a riva

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New post 26 Nov 2014, 07:32
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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.
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anceer wrote:
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.



stock price of telecom company at the beginning of the last month = x
stock price of rival telecom company at the beginning of the last month = y
thus stock price of telecom company at the end of the month = .9x and stock price of the rival company at the end of the month = 1.1y

we are required to find out \(\frac{1.1y}{x} * 100\)--------------------1)

st.1 not sufficient as nothing is mentioned about x.

st.2 .1y= .9 (.1x)

y/x= 9/10

substitute the value of y/x in 1) we have, required percentage as 99%

hence statement b alone is sufficient to answer the question.
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Re: A telecommunications company’s stock fell 10% last month, while a riva [#permalink]

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New post 26 Nov 2014, 12:34
manpreetsingh86 wrote:
anceer wrote:
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.



stock price of telecom company at the beginning of the last month = x
stock price of rival telecom company at the beginning of the last month = y
thus stock price of telecom company at the end of the month = .9x and stock price of the rival company at the end of the month = 1.1y

we are required to find out \(\frac{1.1y}{x} * 100\)--------------------1)

st.1 not sufficient as nothing is mentioned about y.

st.2 .1y= .9 (.1x)

y/x= 9/10

substitute the value of y/x in 1) we have, required percentage as 99%

hence statement b alone is sufficient to answer the question.



you mean nothing is mentioned about x?
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Re: A telecommunications company’s stock fell 10% last month, while a riva [#permalink]

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New post 26 Nov 2014, 23:50
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An easy way to think about s2 is that it relates the increase in one stock with the decrease in the other. Since both changes are 10% of the original, we can also say it relates the actual values. If we know the ratio of the two original values, we can find the requested ratio if we want to. But this is DS, so we don't want to. ;)
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Re: A telecommunications company’s stock fell 10% last month, while a riva [#permalink]

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New post 27 Nov 2014, 00:09
usre123 wrote:
you mean nothing is mentioned about x?


yes, it was a typo. thanks for pointing that out.
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Re: A telecommunications company’s stock fell 10% last month, while a riva [#permalink]

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New post 08 Mar 2017, 23:55
anceer wrote:
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.


Official solution from Veritas Prep.

The correct response is (B). To find the answer we have to know the telecommunication’s stock value last month)/(the rival company’s stock value today) = (.90)(telecomm)/(rival company) = .9(Telecomm/Rival). Statement (1) is insufficient, because it doesn’t tell us the value of the telecommunications company’s stock. Statement (2) may not give us the two values we need, but it does give us their ratio: (0.1)(rival company) = (0.9)(0.1)(telecomm). Sufficient.
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A telecommunications company’s stock fell 10% last month, while a riva [#permalink]

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New post 09 Mar 2017, 00:09
anceer wrote:
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.


Dear AnthonyRitz & ByjusClasses, Could you help to explain this problem? I am stumped by this question and cannot visualized.
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A telecommunications company’s stock fell 10% last month, while a riva [#permalink]

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New post 09 Mar 2017, 00:56
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Prompt analysis
let the stock price of telecommunication company be x and rival's be y at the beginning of month
at the and of the month, telecommunication company's price decreases by 10% or 0.1x and rivals increased by 10% i.e. 0.1y, hence at the end of this month their prices will be 0.9x and 1.1y respectively

Translation

In order to find the percentage for the expression (1.1y/x) x 100, we need:
1# exact value of x and y
2# relation between x and y
3# two variable, two equations.

Statement analysis

St 1: y = 24, no value of x has been given. INSUFFICIENT. Hence option a and d excluded.

St 2: it is given that
dollar amount increase in rival's sock = (90/100) x amount decrease in telecommunication stock
or 0.1y = 0.9 * 0.1x
or y/x = 0.9
putting this value in the expression (1.1y/x) x 100 we get
1.1*0.9*100 = 99%. ANSWER. hence option c and e also excluded

Option B

I hope this clarify your doubt regarding the question.

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Re: A telecommunications company’s stock fell 10% last month, while a riva [#permalink]

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New post 15 Mar 2017, 15:27
anceer wrote:
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.


If we let the stock value of the rival company at the beginning of last month = x, and the stock value of the telecommunications company at the beginning of last month = y, then we can represent the current value of the rival company’s stock as 1.1x (i.e., with an increase of 0.1x in value) and the current value of the telecommunications company’s stock as 0.9y (with a decrease of 0.1y in value).

We need to determine what percentage the rival company's stock value today is of the telecommunications company’s stock value at the beginning of last month. That is:

(1.1x)/y = ?

Statement One Alone:

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

We know that x = 42; however, without knowing any information regarding the other company, we cannot answer the question. Statement one alone is not sufficient.

Statement Two Alone:

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.

Using the information in statement two, we can create the following equation:

0.1x = 0.9(0.1y)

x = 0.9y

x/y = 0.9

Since we have a value for x/y, statement two alone is sufficient.

Answer: B
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Re: A telecommunications company’s stock fell 10% last month, while a riva   [#permalink] 15 Mar 2017, 15:27
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