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I haven't seen a formal definition -- just what they list in say PR or Kaplan, and what I've read from my Google searches. The best source that I found is the wikipedia page for mode(http://en.wikipedia.org/wiki/Mode_%28statistics%29#Uniqueness_and_definedness). However, this does not answer the que...
- by raleigh
Tue Jul 21, 2009 1:17 pm- Forum: Problem Solving
- Topic: What is the mode of this set ?
- Replies: 8
- Views: 2680
You can ONLY split a root under MULTIPLICATION/DIVISION. The GMAT will always tempt you to split a root on addition/subtraction.
- by raleigh
Mon Jul 20, 2009 5:07 pm- Forum: Problem Solving
- Topic: nevermind.. it was my bad :)
- Replies: 5
- Views: 1572
sqrt[(16)(20) + (8)(32)] =
sqrt[ (2^4)(5*2^2) + (2^3)(2^5)] =
sqrt[5*2^6 + 2^8] =
sqrt[2^6(5 + 2^2)] =
sqrt[2^6]*sqrt[5 + 2^2] =
8*sqrt[9] =
8*3 =
24
You broke some rule of algebra if you got D. Solving a problem in different way must yield the same answer. How did you get D?
- by raleigh
Mon Jul 20, 2009 4:00 pm- Forum: Problem Solving
- Topic: nevermind.. it was my bad :)
- Replies: 5
- Views: 1572
The mode is defined to be the number in a number set that occurs most frequently.
The most frequent a number appears in this set is 1 time. Numbers 1, 2, and 3 satisfy this so this set has 3 modes: 1, 2, and 3.
- by raleigh
Mon Jul 20, 2009 1:53 pm- Forum: Problem Solving
- Topic: What is the mode of this set ?
- Replies: 8
- Views: 2680
Since the sequence is evenly spaced, we know that the mean=median=mean of first and last term. Let x = first term. Since there are 18 terms in the sequence, and the sequence is made up of odd consecutive terms, we know that the last term can be represented as x + 2*17 = x + 34. mean = mean of first ...
- by raleigh
Mon Jul 20, 2009 1:45 pm- Forum: Problem Solving
- Topic: Averages
- Replies: 4
- Views: 4653
Re: standard deviation for the original 5 numbers?
A= (X6 - mean)^2 + (X7 - mean)^2 This question is about standard deviation, and you already calculated it to be sqrt(8). Forget variance. Standard deviation is the measure of the spread from the mean to the points in the data set. This spread is about sqrt(8)= 2sqrt(2) ~ 2 * 1.4 = 2.8. You noted th...
- by raleigh
Mon Jul 20, 2009 7:17 am- Forum: Problem Solving
- Topic: standard deviation for the original 5 numbers?
- Replies: 4
- Views: 1258
Obviously, the interest from the first year is 10,000(x/100). However, at the end of the first year, you have 10,000(1+x/100). You'll have 10,000(1+x/100)(x/100) interest from the second year. I think my problem is that is actually compound interest, not simple interest. I must have just overlooked ...
- by raleigh
Sun Jul 05, 2009 1:32 pm- Forum: Problem Solving
- Topic: Simple Annual Interest
- Replies: 3
- Views: 6780
Simple Annual Interest
If $10,000 is invested at x simple percent annual interest for n years, which of the following represents the total amount of interest, in dollars, that will be earned by this investment in n years?
A. (10,000x^n)
B. 10,000(x/100)^n
C. 10,000n(x/100)
D. 10,000(1 + x/100)^n
E. 10,000n(1+x/100)
OA:C
- by raleigh
Sun Jul 05, 2009 12:03 pm- Forum: Problem Solving
- Topic: Simple Annual Interest
- Replies: 3
- Views: 6780
This problem owned me when I took GMAT Prep 1 to see where I was at. This is one of the hardest problems on the GMAT Prep. You can find solutions to most of the GMAT prep problems with the search. Ian wrote a great solution to this problem.
http://www.beatthegmat.com/gmat-prep-q-t14339.html
- by raleigh
Fri Jun 19, 2009 5:30 pm- Forum: Problem Solving
- Topic: Range of a Prime number?
- Replies: 1
- Views: 1231
Value of y^3
It's one of those problems that can trick you if you rush. I got this in the MGMAT question bank. I thought it was pretty good so I'm sharing it.
If x is not equal to y and if y=x^(1/2), what is the value of y^3 ?
(1) x = y^x
(2) x^3 = 8
OA D
- by raleigh
Fri Jun 19, 2009 5:13 pm- Forum: Data Sufficiency
- Topic: Value of y^3
- Replies: 1
- Views: 1103
(1) Consider 25, 25, 25, 125, 300. The mean is 100, and exactly 2 integers is greater than 100. Now consider 25, 25, 125, 125, 200. The mean is 100, and 3 integers are greater than 100. This is insufficient. (2) Note that none of the numbers that we selected for (1) are equal to 100. Apply those cho...
- by raleigh
Thu Jun 18, 2009 7:53 pm- Forum: Data Sufficiency
- Topic: data sufficiency question: (PLEASE HELP)
- Replies: 6
- Views: 1476
Princeton Review is definitely wrong. 
It's unfortunate that Kaplan and Princeton Review books aren't edited like the OG.
- by raleigh
Thu Jun 18, 2009 7:35 pm- Forum: Data Sufficiency
- Topic: data sufficiency question: (PLEASE HELP)
- Replies: 6
- Views: 1476
(1) Since 3 of the numbers are less than 50 we know that only 1 is greater than 100. So the answer to the question is no. This is sufficient. (2) Consider 99, 99, 101, 101. Exactly two numbers are greater than 100 and the mean is 100. Now consider 50, 50, 50, 250. Only one number is greater than 100...
- by raleigh
Thu Jun 18, 2009 7:06 pm- Forum: Data Sufficiency
- Topic: data sufficiency question: (PLEASE HELP)
- Replies: 6
- Views: 1476
You're welcome. Please take the time to write out the exact question so everything is clear to the people helping.
- by raleigh
Thu Jun 18, 2009 11:53 am- Forum: Problem Solving
- Topic: GMATPrep Question Help...
- Replies: 6
- Views: 1458
I like that in an evenly spaced set, mean = median = (largest term + smallest term)/2.
It gives you a bunch of ways to approach a question about evenly spaced sets.
- by raleigh
Thu Jun 18, 2009 9:47 am- Forum: GMAT Math
- Topic: What's YOUR favorite GMAT Quantitative shortcut?
- Replies: 21
- Views: 6372