Last visit was: 05 Nov 2024, 17:29 It is currently 05 Nov 2024, 17:29

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
Verbal Expert
Joined: 18 Apr 2015
Posts: 29894
Own Kudos [?]: 36130 [28]
Given Kudos: 25919
Send PM
Most Helpful Community Reply
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Own Kudos [?]: 12176 [14]
Given Kudos: 136
Send PM
avatar
Manager
Manager
Joined: 22 Jan 2020
Posts: 120
Own Kudos [?]: 239 [6]
Given Kudos: 10
Send PM
General Discussion
Verbal Expert
Joined: 18 Apr 2015
Posts: 29894
Own Kudos [?]: 36130 [0]
Given Kudos: 25919
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
Expert Reply
Post A Detailed Correct Solution For The Above Questions And Get A Kudos.
Question From Our New Project: GRE Quant Challenge Questions Daily - NEW EDITION!
User avatar
Manager
Manager
Joined: 02 May 2020
Posts: 91
Own Kudos [?]: 140 [1]
Given Kudos: 0
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
1
Why is A correct answer?
Is it because the length of both the intervals (-30 to 150 and -60 to 120) is same but the first one is more uniformly arranged about the mean?
Verbal Expert
Joined: 18 Apr 2015
Posts: 29894
Own Kudos [?]: 36130 [0]
Given Kudos: 25919
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
Expert Reply
The mean of the distribution, 70, falls within both of those ranges. However, the range for Quantity B lies farther to the left side of the bell curve, therefore encompassing more of the tail of the normal distribution.
User avatar
Senior Manager
Senior Manager
Joined: 10 Feb 2020
Posts: 496
Own Kudos [?]: 346 [1]
Given Kudos: 299
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
1
If anyone can explain with diagram plz
avatar
Manager
Manager
Joined: 22 Jan 2020
Posts: 120
Own Kudos [?]: 239 [0]
Given Kudos: 10
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
3
Attachment:
bellCurves.PNG
bellCurves.PNG [ 20.27 KiB | Viewed 16315 times ]
User avatar
Senior Manager
Senior Manager
Joined: 10 Feb 2020
Posts: 496
Own Kudos [?]: 346 [0]
Given Kudos: 299
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
chacinluis wrote:
Attachment:
bellCurves.PNG

Thank you very much
Intern
Intern
Joined: 10 Apr 2021
Posts: 16
Own Kudos [?]: 11 [1]
Given Kudos: 155
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
1
GreenlightTestPrep
Hi sir,

Can you please explain this question? How can we know which range is tighter around the mean if we don't have the standard deviation?

Thanks in advance!
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Own Kudos [?]: 12176 [1]
Given Kudos: 136
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
1
godxyz wrote:
GreenlightTestPrep
Hi sir,

Can you please explain this question? How can we know which range is tighter around the mean if we don't have the standard deviation?

Thanks in advance!


Done! (see above)
Intern
Intern
Joined: 08 Aug 2022
Posts: 49
Own Kudos [?]: 36 [1]
Given Kudos: 98
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
1
Both intervals contain the numbers from -30 to 120, so they are the same in that regard, and we can ignore those values when comparing.

So what we need to compare is the interval 120 to 150 in option A versus the interval of -60 to -30 in option B. Both have a range of 30. However, the area under the normal curve (the "probability") is larger closer to the mean and smaller further away. So whichever of these intervals is closer to the mean of 70 will have a higher probability.

Option A is a distance of 50 to 80 from the mean (120-70 and 150-70) . Option B is a distance of 100 to 130 from the mean (70-(-30) and 70-(-60). So the normal curve is taller in the area between 120 and 150, since that is closer to the mean, thus the probability in that region is greater.

The answer is Option A.
User avatar
GRE Prep Club Legend
GRE Prep Club Legend
Joined: 07 Jan 2021
Posts: 5006
Own Kudos [?]: 74 [0]
Given Kudos: 0
Send PM
Re: The random variable X has a normal distribution with a mean [#permalink]
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep 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.
Prep Club for GRE Bot
Re: The random variable X has a normal distribution with a mean [#permalink]
Moderators:
GRE Instructor
77 posts
GRE Forum Moderator
37 posts
Moderator
1111 posts
GRE Instructor
228 posts

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