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.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

A set of data consists of the following 5 numbers: 0,2,4,6 [#permalink]
24 Jan 2008, 15:08

1

This post received KUDOS

1

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct
0% (00:00) wrong based on 0 sessions

A set of data consists of the following 5 numbers: 0,2,4,6 and 8. Which 2 numbers, if added to create a set of 7 numbers, will result in a new standard deviation that is closest to the standard deviation for of the 5 original numbers?

A) -1 and 9 B) 4 and 4 C) 3 and 5 D) 2 and 6 E) 0 and 8

Sorry, I mistook and wrote d instead of 4 in B.

Last edited by netcaesar on 25 Jan 2008, 08:36, edited 1 time in total.

Re: PS: Standard Deviation [#permalink]
24 Jan 2008, 20:29

GMATBLACKBELT wrote:

eschn3am wrote:

Average is 4. Each of the pairs has an average of 4 except for B. which is 4 and D.

Answer B

??????? How can you deduce that (4+D)/2 isn't going to be 4?

I can't. It's a case of knowing that all the other ones are 4 for sure, so I'll put my money on the one that might be something else.

I agree that it's bizarre logic though. I'm thinking there must be something wrong with either the question, my logic or my understanding of the question because choosing B for being the lesser of 5 evils is ridiculous.

Re: PS: Standard Deviation [#permalink]
29 Jan 2008, 14:52

netcaesar wrote:

A set of data consists of the following 5 numbers: 0,2,4,6 and 8. Which 2 numbers, if added to create a set of 7 numbers, will result in a new standard deviation that is closest to the standard deviation for of the 5 original numbers?

A) -1 and 9 B) 4 and 4 C) 3 and 5 D) 2 and 6 E) 0 and 8

Sorry, I mistook and wrote d instead of 4 in B.

Average of 5 numbers = 4 The way I look at it is each of the choices will not affect the average (it remains 4 as the total will be 28 for 7 numbers), but the standard deviation will be least affected by choice B simply because (4-4)^2 will not affect the overall summation.