Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 24 Jul 2010
Posts: 85

The scores on a certain history test are shown above. How [#permalink]
Show Tags
Updated on: 10 Apr 2013, 01:25
2
This post received KUDOS
3
This post was BOOKMARKED
Question Stats:
76% (00:51) correct 24% (00:57) wrong based on 386 sessions
HideShow timer Statistics
40, 45, 45, 50, 50, 60, 70, 75, 95, 100 The scores on a certain history test are shown above. How many scores were greater than the median score but less than the mean score? A. None B. One C. Two D. Three E. Four
Official Answer and Stats are available only to registered users. Register/ Login.
Originally posted by score780 on 10 Apr 2013, 01:21.
Last edited by Bunuel on 10 Apr 2013, 01:25, edited 1 time in total.
Renamed the topic and edited the tags.



Math Expert
Joined: 02 Sep 2009
Posts: 45429

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
10 Apr 2013, 01:33
score780 wrote: 40, 45, 45, 50, 50, 60, 70, 75, 95, 100
The scores on a certain history test are shown above. How many scores were greater than the median score but less than the mean score?
A. None B. One C. Two D. Three E. Four The median = (the average of two middle terms) = (50 + 60)/2 = 55. The mean = (the sum)/(# of terms) = 630/10 = 63. Only 60 is between 55 and 63. Answer: B.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Manager
Joined: 24 Jul 2010
Posts: 85

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
10 Apr 2013, 01:37
Bunuel wrote: score780 wrote: 40, 45, 45, 50, 50, 60, 70, 75, 95, 100
The scores on a certain history test are shown above. How many scores were greater than the median score but less than the mean score?
A. None B. One C. Two D. Three E. Four The median = (the average of two middle terms) = (50 + 60)/2 = 55. The mean = (the sum)/(# of terms) = 630/10 = 63. Only 60 is between 55 and 63. Answer: B. Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it?



Intern
Joined: 01 Apr 2013
Posts: 19

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
10 Apr 2013, 02:40
Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it?[/quote]
In this problem , yes you can calculate it in 10 seconds , if you can observe the total number of terms is 10. so since every number is a multiple of 10 you can do it easily .
If there is a general method do let me know.



Manager
Joined: 24 Jul 2010
Posts: 85

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
10 Apr 2013, 02:46
1
This post received KUDOS
venkat18290 wrote: Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it? In this problem , yes you can calculate it in 10 seconds , if you can observe the total number of terms is 10. so since every number is a multiple of 10 you can do it easily . If there is a general method do let me know.[/quote] Ok got it, thanks



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8079
Location: Pune, India

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
11 Apr 2013, 08:03
score780 wrote: Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it?
40, 45, 45, 50, 50, 60, 70, 75, 95, 100 You can use deviations to find the mean here. Assume that the mean is 60 since it's kind of in the middle. Now notice that 50 is 10 less than 60 and 70 is 10 more so ignore both. Now 40, 45, 45, 50 together are 60 away from 60 while 75, 95, 100 are 90 away from 60. So we have a total of 90  60 = 30 deviation from 60. Since there are 10 numbers, the average must be 30/10 = 3 more than 60 i.e it must be 63. Check this for more on this method: http://www.veritasprep.com/blog/2012/05 ... eviations/For a general discussion on mean, see http://www.veritasprep.com/blog/2012/04 ... eticmean/
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8079
Location: Pune, India

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
09 Feb 2015, 01:10
VeritasPrepKarishma wrote: score780 wrote: Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it?
40, 45, 45, 50, 50, 60, 70, 75, 95, 100 You can use deviations to find the mean here. Assume that the mean is 60 since it's kind of in the middle. Now notice that 50 is 10 less than 60 and 70 is 10 more so ignore both. Now 40, 45, 45, 50 together are 60 away from 60 while 75, 95, 100 are 90 away from 60. So we have a total of 90  60 = 30 deviation from 60. Since there are 10 numbers, the average must be 30/10 = 3 more than 60 i.e it must be 63. Check this for more on this method: http://www.veritasprep.com/blog/2012/05 ... eviations/For a general discussion on mean, see http://www.veritasprep.com/blog/2012/04 ... eticmean/Quote: why did you not consider the second 50 in your calculation? Because then 40,45,45,50,50 would be 70 away from 60.
There is a second 50 which is 10 away from 60 and then there is a 70 which is also 10 away from 60. So together, they cancel off each other and give an average of 60 only. Or consider that the numbers on the left are 70 away but then the numbers on the right are 100 away since there is a 70 also which we haven't considered. Hence, overall, we still have 30 extra which will be distributed evenly among the 10 numbers. So the average will be 63.
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Manager
Status: Build your own dreams,Otherwise some one else will hire you to build there's.
Joined: 30 Apr 2015
Posts: 92
Location: India
Concentration: Finance
GMAT 1: 590 Q45 V26 GMAT 2: 660 Q47 V34
GPA: 3.68

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
22 Feb 2016, 08:24
I think iam going crazy......I am able to solve 700 level mistake.but fail to do 600700.Always doing some HOMER(Simpson) mistake......... ;(
_________________
"Follow your heart and realize that your dream is a dream for a reason" Dori Roberts



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8079
Location: Pune, India

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
22 Feb 2016, 21:27
mahakmalik wrote: I think iam going crazy......I am able to solve 700 level mistake.but fail to do 600700.Always doing some HOMER(Simpson) mistake.........
;( Slow down a bit then. When you are done with the question, take another look at the problem and ensure you have answered what was asked. You will catch up on time again after some practice.
_________________
Karishma Veritas Prep  GMAT Instructor My Blog
Get started with Veritas Prep GMAT On Demand for $199
Veritas Prep Reviews



Intern
Joined: 14 Jun 2016
Posts: 20
Location: United States
WE: Engineering (Pharmaceuticals and Biotech)

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
12 Sep 2016, 12:29
1
This post received KUDOS
1
This post was BOOKMARKED
score780 wrote: Bunuel wrote: score780 wrote: 40, 45, 45, 50, 50, 60, 70, 75, 95, 100
The scores on a certain history test are shown above. How many scores were greater than the median score but less than the mean score?
A. None B. One C. Two D. Three E. Four The median = (the average of two middle terms) = (50 + 60)/2 = 55. The mean = (the sum)/(# of terms) = 630/10 = 63. Only 60 is between 55 and 63. Answer: B. Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it? I think you can use a baseline method. Choose 40 as baseline. So differences between every other number and 40 are: 5, 5, 10, 10, 20, 30, 35, 55, 60. Sum all of them and divide by 10 = 23. Add to 40 = 63, which is the average of all 10 numbers.



NonHuman User
Joined: 09 Sep 2013
Posts: 6856

Re: The scores on a certain history test are shown above. How [#permalink]
Show Tags
28 Oct 2017, 09:07
Hello from the GMAT Club BumpBot! Thanks to another GMAT 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.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: The scores on a certain history test are shown above. How
[#permalink]
28 Oct 2017, 09:07






