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

It is currently 18 Jun 2019, 08:29

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

The closing price of Stock X changed on each trading day last month. T

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Board of Directors
User avatar
D
Joined: 01 Sep 2010
Posts: 3361
The closing price of Stock X changed on each trading day last month. T  [#permalink]

Show Tags

New post 25 Jul 2017, 11:45
5
Top Contributor
99
00:00
A
B
C
D
E

Difficulty:

  85% (hard)

Question Stats:

56% (02:38) correct 44% (02:28) wrong based on 957 sessions

HideShow timer Statistics

The closing price of Stock X changed on each trading day last month. The percent change in the closing price of Stock X from the first trading day last month to each of the other trading days last month was less than 50 percent. If the closing price on the second trading day last month was $ 10.00, which of the following CANNOT be the closing price on the last trading day last month?

A. $ 3.00

B. $ 9.00

C. $ 19.00

D. $ 24.00

E. $ 29.00

_________________
Most Helpful Expert Reply
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2823
Re: The closing price of Stock X changed on each trading day last month. T  [#permalink]

Show Tags

New post 09 Aug 2017, 13:36
26
1
17
carcass wrote:
The closing price of Stock X changed on each trading day last month. The percent change in the closing price of Stock X from the first trading day last month to each of the other trading days last month was less than 50 percent. If the closing price on the second trading day last month was $ 10.00, which of the following CANNOT be the closing price on the last trading day last month?

A. $ 3.00

B. $ 9.00

C. $ 19.00

D. $ 24.00

E. $ 29.00


Let us begin by determining a range for the closing price on the first trading day of the last month.

Let us denote the closing price on the first day by x. We are given that the closing price on the second trading day was $10. We know x could increase by no more than 50% to become 10, or x could decrease by no more than 50% to become 10.

If x increases by 50% to become 10, then (1.5)x = 10 and hence x = 6.67.

If x decreases by 50% to become 10, then (0.5)x = 10 and hence x = 20.

We see that the closing price on the first day could be any value between 6.67 and 20.

Now, let’s determine upper and lower bounds for the closing price on the last trading day of last month.

Since the closing price on the last trading day can be at most 50% more than the closing price of the first day of last month, the closing price on the last day of last month must be less than (1.5)20 = 30.

Since the closing price on the last trading day can be at most 50% less than the closing price of the first day of last month, the closing price on the last day of last month must be greater than (0.5)(6.67) ≈ 3.3.

Looking at the answer choices, the only price that is not greater than 3.3 and less than 30 is 3.

Answer: A
_________________

Jeffrey Miller

Head of GMAT Instruction

Jeff@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Most Helpful Community Reply
Director
Director
User avatar
D
Affiliations: IIT Dhanbad
Joined: 13 Mar 2017
Posts: 729
Location: India
Concentration: General Management, Entrepreneurship
GPA: 3.8
WE: Engineering (Energy and Utilities)
Re: The closing price of Stock X changed on each trading day last month. T  [#permalink]

Show Tags

New post 29 Jul 2017, 20:22
15
5
carcass wrote:
The closing price of Stock X changed on each trading day last month. The percent change in the closing price of Stock X from the first trading day last month to each of the other trading days last month was less than 50 percent. If the closing price on the second trading day last month was $ 10.00, which of the following CANNOT be the closing price on the last trading day last month?

A. $ 3.00

B. $ 9.00

C. $ 19.00

D. $ 24.00

E. $ 29.00


Price of stock X on 2nd day was $10
Since %ge change of first day w.r.t any other day of the month cannot be more than 50%
So, y<Price of stock X on 1st day <x
Now ((10-y)/y )*100 = 50
-> (10-y)/y = .5
-> 10 - y = .5y
y = 10 /1.5 = 6.666

x-10 /x = .5
x -10 = .5x
.5x = 10
x = 20

So, 6.6666< Price of stock X on 1st day < 20
Since price on other days can vary by only 50% from the 1st day.
So, 6.6666*0.5 < Price of stock X on other days < 20*1.5
3.3333< Price of stock X on other days < 30

Only option A i.e. $3 doesn't lies in this range.

Hence Answer A

Appreciate if you liked my solution ... :)
_________________
CAT 2017 (98.95) & 2018 (98.91) : 99th percentiler
UPSC Aspirants : Get my app UPSC Important News Reader from Play store.

MBA Social Network : WebMaggu


Appreciate by Clicking +1 Kudos ( Lets be more generous friends.)



What I believe is : "Nothing is Impossible, Even Impossible says I'm Possible" : "Stay Hungry, Stay Foolish".
General Discussion
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7757
The closing price of Stock X changed on each trading day last month. T  [#permalink]

Show Tags

New post 29 Jul 2017, 21:20
6
4
priyesh92 wrote:
Hi,

Can someone please explain how to solve this problem?

Thanks in advance



Hi..

Although the solution is already provided, just a point for knowledge..

whenever we are looking at a Q like this, where there is an open ended range , for example less than 50% here..
ONE of the extremes should be the answer..

here it is either 3 or 29..
so your probability of answering is now 50%..


otherwise..
10 could be after increase from 1st day..
so \(x+0.5x>10.... 1.5x>10 .... x>\frac{10}{1.5}....x>6.67\)
now the lowest value possible is \(6.67*0.5 = 3.33\)
straight 3 is out..

otherwise if 10 has come after decrease from 1st day..
x-0.5x<10....0.5x<10...x<20
upper end is 20*1.5=30..

ans A
_________________
Intern
Intern
avatar
B
Joined: 01 Dec 2017
Posts: 13
Location: Italy
Schools: IMD Jan'18
GMAT 1: 680 Q46 V38
GPA: 4
Re: The closing price of Stock X changed on each trading day last month. T  [#permalink]

Show Tags

New post 27 Feb 2018, 07:03
Hi, I got this question right in the end, but I don't think is properly written by GMAT Guide...I mean, the question says the "percent change from the FIRST day to any other day is less than 50%"; so why are we considering also negative changes of -50%? I thought that we could use only this expression to translate the stem:

\(\frac{(PriceOld-PriceNew)}{Price Old}<0.5\) ,

which means that Price old should be always greater than 10 dollars....of course that's not the case otherwise there would be more than one answer possible but I am not sure this question is properly written...? Is it may be because it used the word "change" instead of increase or decrease ?

Thank you for your opinion on the merit


chetan2u wrote:
priyesh92 wrote:
Hi,

Can someone please explain how to solve this problem?

Thanks in advance



Hi..

Although the solution is already provided, just a point for knowledge..

whenever we are looking at a Q like this, where there is an open ended range , for example less than 50% here..
ONE of the extremes should be the answer..

here it is either 3 or 29..
so your probability of answering is now 50%..


otherwise..
10 could be after increase from 1st day..
so \(x+0.5x>10.... 1.5x>10 .... x>\frac{10}{1.5}....x>6.67\)
now the lowest value possible is \(6.67*0.5 = 3.33\)
straight 3 is out..

otherwise if 10 has come after decrease from 1st day..
x-0.5x<10....0.5x<10...x<20
upper end is 20*1.5=30..

ans A
Manager
Manager
User avatar
B
Status: IF YOU CAN DREAM IT, YOU CAN DO IT
Joined: 03 Jul 2017
Posts: 190
Location: India
Concentration: Finance, International Business
Re: The closing price of Stock X changed on each trading day last month. T  [#permalink]

Show Tags

New post 18 May 2018, 09:58
2
One doubt. So is the question suggesting that the percent change is with respect to the price on the first day?? I thought the price of the stock on the last day if we assume that there were 30 days depends on the price of the stock on the 29th day. Where am I going wrong. Kindly help. Thanks
Intern
Intern
avatar
B
Joined: 01 Mar 2018
Posts: 1
Re: The closing price of Stock X changed on each trading day last month. T  [#permalink]

Show Tags

New post 06 Sep 2018, 04:01
1
I was thinking the same thing as reply above. Although the solution is quite simple but the wording of the question here really confused me. Should’t “Last trading day of last month” comes after first and second trading day of last month ??

Posted from my mobile device
Manager
Manager
avatar
B
Joined: 18 Aug 2017
Posts: 75
GMAT ToolKit User
Re: The closing price of Stock X changed on each trading day last month. T  [#permalink]

Show Tags

New post 11 Nov 2018, 08:07
1
The percent change in the closing price of Stock X from the first trading day last month to each of the other trading days last month was less than 50 percent.

Does this mean that less than 50 percent is only based on the first and the last day?

I understand that less than 50 percent for each day
Ex Price at day 2 is 100
Price at day 3 cannot be more than or less than 50 of that of day2
and Price at day 4 cannot be more than or less than 50 of that of day3
And so on


Please correct me if I'm wrong
Intern
Intern
User avatar
B
Joined: 10 Feb 2018
Posts: 10
GMAT 1: 670 Q44 V38
GMAT 2: 710 Q48 V40
WE: Project Management (Health Care)
Re: The closing price of Stock X changed on each trading day last month. T  [#permalink]

Show Tags

New post 15 Dec 2018, 09:59
1
longhaul123 wrote:
One doubt. So is the question suggesting that the percent change is with respect to the price on the first day?? I thought the price of the stock on the last day if we assume that there were 30 days depends on the price of the stock on the 29th day. Where am I going wrong. Kindly help. Thanks


I believe the information you are referring t is in this sentence "The percent change in the closing price of Stock X from the first trading day last month to each of the other trading days last month was less than 50 percent."

I think you are saying that the percent change is less than 50% from each day to the next day, but the section above is saying that the price cannot change more or less that 50% from the first day.

For example day 2 is $10, so to find the range of x for the first day we need 2 equations:
x(1.5) = 10 .... x=6.67
x(.5) = 10 .... x=20

This is the range of values for the first day, 6.67 < x < 20, so every other day in the month can not vary more than 50% from these extremes.

6.67*(.5)<x<20*(1.5) .... 3.33 < x < 30

So this 3.33 to 30 is not only the range for the last day of the month, it is also the range for all the days of the month (besides day 2 which is known) because all days can not vary by more than 50% from the first day.
GMAT Club Bot
Re: The closing price of Stock X changed on each trading day last month. T   [#permalink] 15 Dec 2018, 09:59
Display posts from previous: Sort by

The closing price of Stock X changed on each trading day last month. T

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne