5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
Statistics
This topic has expert replies
The residents of Town X participated in a survey to determine the no. of hours per week each resident spent watching TV. The distribution of the results of the survey had a mean of 21 hours and a standard deviation of 6 hours.The no. of hours that Pat,A resident of Town X,watched TV last week was between 1&2 standard deviation below mean. so, the no. of hours he watched TV last week is?
GMAT/MBA Expert
-
Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
When posting, please provide the ENTIRE question, including the answer choices.
Here's a link with a nice solution: https://www.beatthegmat.com/an-issue-reg ... 75194.html
Also, here's a video that covers the necessary concepts/skills to answer this question: https://www.gmatprepnow.com/module/gmat ... /video/809
Cheers,
Brent
Here's a link with a nice solution: https://www.beatthegmat.com/an-issue-reg ... 75194.html
Also, here's a video that covers the necessary concepts/skills to answer this question: https://www.gmatprepnow.com/module/gmat ... /video/809
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
GMAT/MBA Expert
-
[email protected]
- Elite Legendary Member
- Posts: 10392
- Joined: Sun Jun 23, 2013 6:38 pm
- Location: Palo Alto, CA
- Thanked: 2867 times
- Followed by:511 members
- GMAT Score:800
Hi Apoorva@5,
In the real world, Standard Deviation is based on a rather 'thick' math formula; thankfully, the GMAT will never ask you to use that formula or perform a standard deviation calculation that is all that complicated. SD is a rather rare subject on Test Day (you'll likely see it on just one question) and you'll be tested more on your general knowledge of the concept than on anything else.
In this particular prompt, we're given the mean (21 hours) and the SD (6 hours). We're asked for a value that is BETWEEN 1 and 2 SDs BELOW the mean. Since SD goes in both 'directions' from the mean, we would have the following results:
1 SD away would be (21-6) = 15 and (21+6) = 27
2 SDs away would be 21-12) = 9 and (21+12) = 33
Since we're specifically asked for BELOW the mean, we'd be looking for an answer that was between 9 and 15.
GMAT assassins aren't born, they're made,
Rich
In the real world, Standard Deviation is based on a rather 'thick' math formula; thankfully, the GMAT will never ask you to use that formula or perform a standard deviation calculation that is all that complicated. SD is a rather rare subject on Test Day (you'll likely see it on just one question) and you'll be tested more on your general knowledge of the concept than on anything else.
In this particular prompt, we're given the mean (21 hours) and the SD (6 hours). We're asked for a value that is BETWEEN 1 and 2 SDs BELOW the mean. Since SD goes in both 'directions' from the mean, we would have the following results:
1 SD away would be (21-6) = 15 and (21+6) = 27
2 SDs away would be 21-12) = 9 and (21+12) = 33
Since we're specifically asked for BELOW the mean, we'd be looking for an answer that was between 9 and 15.
GMAT assassins aren't born, they're made,
Rich
-
Matt@VeritasPrep
- GMAT Instructor
- Posts: 2630
- Joined: Wed Sep 12, 2012 3:32 pm
- Location: East Bay all the way
- Thanked: 625 times
- Followed by:119 members
- GMAT Score:780
If the mean is 21 and the sd is 6, then
mean = 21
one sd below = 21 - 6 = 15
two sds below = 21 - 2*6 = 9
so the answer should be between 9 and 15.
mean = 21
one sd below = 21 - 6 = 15
two sds below = 21 - 2*6 = 9
so the answer should be between 9 and 15.
