Last visit was: 18 Dec 2024, 00:58 It is currently 18 Dec 2024, 00:58

Close

GRE Prep 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 GRE 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
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3258 [2]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
Most Helpful Community Reply
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3258 [1]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
General Discussion
Manager
Manager
Joined: 18 Jan 2021
Posts: 81
Own Kudos [?]: 20 [0]
Given Kudos: 103
Send PM
Senior Manager
Senior Manager
Joined: 03 Dec 2020
Posts: 440
Own Kudos [?]: 61 [0]
Given Kudos: 68
Send PM
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
koala wrote:
To find the median we have to arrange the values in ascending order first. How would we even achieve this? I know plugging n the numbers won't work. What is the strategy behind this question?

to ans your question , let see -
30 days were given, to find median of 30 days is avg of 15th and 16th day.
we are provided with equations for 1st half of month and other 15 days for remaining half.
for first equation, put x=15 you will get 6 and put 15 in second equation you will 6.85
taking average 6 and 6.85 is less than 7.85 .
hence option b is your ans.
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3258 [0]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
void wrote:
koala wrote:
To find the median we have to arrange the values in ascending order first. How would we even achieve this? I know plugging n the numbers won't work. What is the strategy behind this question?

to ans your question , let see -
30 days were given, to find median of 30 days is avg of 15th and 16th day.
we are provided with equations for 1st half of month and other 15 days for remaining half.
for first equation, put x=15 you will get 6 and put 15 in second equation you will 6.85
taking average 6 and 6.85 is less than 7.85 .
hence option b is your ans.


When x = 15, you will get f(x) = 8
Why do we need to put x = 15 again in the second equation?
Senior Manager
Senior Manager
Joined: 03 Dec 2020
Posts: 440
Own Kudos [?]: 61 [0]
Given Kudos: 68
Send PM
The daily closing price of one barrel of oil for first 15 days of a [#permalink]
KarunMendiratta wrote:
void wrote:
koala wrote:
To find the median we have to arrange the values in ascending order first. How would we even achieve this? I know plugging n the numbers won't work. What is the strategy behind this question?

to ans your question , let see -
30 days were given, to find median of 30 days is avg of 15th and 16th day.
we are provided with equations for 1st half of month and other 15 days for remaining half.
for first equation, put x=15 you will get 6 and put 15 in second equation you will 6.85
taking average 6 and 6.85 is less than 7.85 .
hence option b is your ans.


When x = 15, you will get f(x) = 8
Why do we need to put x = 15 again in the second equation?

i am not sure, it will explain or justifying explaination....but let go with it..
i just assume that 15 days as one quantity and another 15 days which, i start number from 1 to 15. I did it because question says two half and start number so i start number from 1 to 15 and same way for another number. if you put x=30 in seond equation will still valuse about 4.75 and average of 4.75+6 is is less than 7.85..
Manager
Manager
Joined: 18 Jan 2021
Posts: 81
Own Kudos [?]: 20 [1]
Given Kudos: 103
Send PM
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
1
Shouldn't we substitute 15 in equation 1(as the question mentions there are 2 15 days period) and then 1 in equation 2 and then find the mean.
Now eq.1 gives 8 and eq.2 gives \(\frac{62}{7}\) which gives us and average of \(\frac{59}{7}\) . So option A should be correct.
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3258 [0]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
yagneshward
Can you please explain here why the OA has to be Option (A)?
avatar
Intern
Intern
Joined: 15 Nov 2020
Posts: 2
Own Kudos [?]: 1 [0]
Given Kudos: 2
Send PM
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
The median for the 30 days will be the mean of the 15th and 16th days.

For 15th day, f(x)= 0.4x+2, where x = 15. ====> On substituting x=15 in the function, we get 8.

For 16th day, f(x) = (-x / 7 ) + 9, where x=16.==> On substituting x= 16 in the function, we get 6.714285714285714

The median will be ( 8 + 6.714285714285714 ) / 2 = 7.357142857142858

7.357142857142858 is greater than 7.35.

So, therefore Option A should be the right answer.
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3258 [0]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
yagneshward wrote:
The median for the 30 days will be the mean of the 15th and 16th days.

For 15th day, f(x)= 0.4x+2, where x = 15. ====> On substituting x=15 in the function, we get 8.

For 16th day, f(x) = (-x / 7 ) + 9, where x=16.==> On substituting x= 16 in the function, we get 6.714285714285714

The median will be ( 8 + 6.714285714285714 ) / 2 = 7.357142857142858

7.357142857142858 is greater than 7.35.

So, therefore Option A should be the right answer.


On substituting x= 16 in the function, we get 6.714285714285714 - Correct!
But is it the least value for the second equation?
avatar
Intern
Intern
Joined: 15 Nov 2020
Posts: 2
Own Kudos [?]: 1 [1]
Given Kudos: 2
Send PM
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
1
Understood my mistake. Thanks for the explanation.
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3258 [2]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
2
yagneshward wrote:
Understood my mistake. Thanks for the explanation.


Anytime :thumbsup:
Intern
Intern
Joined: 19 Oct 2024
Posts: 16
Own Kudos [?]: 7 [0]
Given Kudos: 70
Send PM
The daily closing price of one barrel of oil for first 15 days of a [#permalink]
KarunMendiratta wrote:
Explanation:

For the first 15 days let us calculate the minimum and maximum closing price

Min. price is when \(x = 1\)
\(f(x) = 0.4(1) + 2 = 2.4\)

Max. price is when \(x = 15\)
\(f(x) = 0.4(15) + 2 = 8\)

Now, let us calculate the minimum and maximum closing price for last 15 days

Min. price is when \(x = 30\)
\(f(x) = \frac{−30}{7} + 9 = 4.71\)

Max. price is when \(x = 16\)
\(f(x) = \frac{−16}{7} + 9 = 6.71\)

Now the median (M) for the 30 day period would be the average of 15th and 16th term arranged in ascending order
i.e. (2.4) .......... (4.71) (M) (6.71) .......... (8)
\(M = \frac{4.71 + 6.71}{2} = 5.71\)

Col. A: 5.71
Col. B: 7.35

Hence, option B


How do you know that 4.71 and 6.71 are the middle numbers?
Verbal Expert
Joined: 18 Apr 2015
Posts: 30349
Own Kudos [?]: 36746 [0]
Given Kudos: 26080
Send PM
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
Expert Reply
Now the median (M) for the 30 day period would be the average of 15th and 16th term arranged in ascending order

i.e. (2.4) .......... (4.71) (M) (6.71) .......... (8)
Prep Club for GRE Bot
Re: The daily closing price of one barrel of oil for first 15 days of a [#permalink]
Moderators:
GRE Instructor
88 posts
GRE Forum Moderator
37 posts
Moderator
1115 posts
GRE Instructor
234 posts

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