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

 It is currently 15 Jul 2018, 23:36

### 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

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

# Urgent - Need Help for One standard Deveiation Question

Author Message
Intern
Joined: 29 Jun 2008
Posts: 15
Urgent - Need Help for One standard Deveiation Question [#permalink]

### Show Tags

12 Jul 2009, 20:42
00:00

Difficulty:

(N/A)

Question Stats:

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

### HideShow timer Statistics

The List consist of the times in seconds that took each of the schoolchildren to run a distance of 400 meters. If the standard deveiation of the 10 running times is 22.4 seconds,rounded to the nearest tenth of a second, how many of the 10 running times are more than one standard deviation below the mean of the 10 running times?

1. One
2. Two
3. Three
4. Four
5. Five

Answer is two, but i dont know how to calcualte this one though it looks simple ... Pleae help me .. have exam in next 3 weeks.

Regards,
Puneet Pareek

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Current Student
Joined: 03 Aug 2006
Posts: 112
Re: Urgent - Need Help for One standard Deveiation Question [#permalink]

### Show Tags

12 Jul 2009, 21:33
Puneet,

Your question is missing the list of the 10 running times in seconds. Once you have that list this is how you would proceed.

1. Calculate the mean (avg) of the 10 numbers

$$\Rightarrow \frac{N1+N2+N3+...+N8+N9+N10}{10}=N_{avg}$$

2. Subtract the SD i.e. 22.4 from the avg

$$\Rightarrow N_{avg}-SD=N_{avg}-22.4$$

Now look for running times in the list that are less than this calculated value. The answer should be the number of values that satisfy the above criteria.
Intern
Joined: 29 Jun 2008
Posts: 15
Re: Urgent - Need Help for One standard Deveiation Question [#permalink]

### Show Tags

14 Jul 2009, 19:27
Hi Nookway,

I got my answer... thanks a ton ... i calculated .. .answer is two only ...

Regards,
Puneet Pareek

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: Urgent - Need Help for One standard Deveiation Question   [#permalink] 14 Jul 2009, 19:27
Display posts from previous: Sort by

# Urgent - Need Help for One standard Deveiation Question

Moderators: chetan2u, niks18, Bunuel, KarishmaB

# Events & Promotions

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.