Search found 83 matches
Ian hit it on the head. (I really like coming after this guy because he's spot on.) The GMAT will require factorials in the context of Combination and Permutation problems. The way those formulas are set up to divide factorials before you actually calculate them. For example: 8_C_3 = 8!/ [3!(8-3)!] ...
- by VP_RedSoxFan
Thu Jul 31, 2008 8:17 am- Forum: GMAT Math
- Topic: Silly question on factorials
- Replies: 3
- Views: 2458
I echo Ian's comments. Not only do you not need ANYthing from the first two and about 1/2 of the third, but trying to apply those techniques on the GMAT will be seriously detrimental. The GMAT problems are designed to reward those who can quickly apply logical thought and algebra in an time-sensitiv...
- by VP_RedSoxFan
Thu Jul 31, 2008 8:06 am- Forum: Problem Solving
- Topic: Algebra - Reference
- Replies: 2
- Views: 1490
Thanks for the catch. I usually do the problems on paper first and then transcribe. Must be my Homer-Simpson-like fat fingers... 
- by VP_RedSoxFan
Thu Jul 31, 2008 7:58 am- Forum: Problem Solving
- Topic: Confusing Workers
- Replies: 3
- Views: 1396
I really like the approach by Mixaela. You'll just have to prove to yourself that subtracting two multiples of 4 leaves a difference that is still a multiple of 4.
You can either know this to be true or you can prove it to yourself with a quick example on test day, i.e. 24-16=8, etc.
- by VP_RedSoxFan
Thu Jul 31, 2008 7:55 am- Forum: Problem Solving
- Topic: Quick solutions to this
- Replies: 3
- Views: 1425
- by VP_RedSoxFan
Thu Jul 31, 2008 7:48 am- Forum: Problem Solving
- Topic: GMAT Prep ? (Multiples and primes)
- Replies: 8
- Views: 3821
If 90 percent of the office has less than 10 years service, then 10% has at least 10 years. We know that there are 16 people with at least 10 years and that represents 10 percent of the workforce. Now we can solve for the number of employees, x, as follows: .1x=16 x=160 If 40 percent have at least 5...
- by VP_RedSoxFan
Thu Jul 31, 2008 7:42 am- Forum: Problem Solving
- Topic: Confusing Workers
- Replies: 3
- Views: 1396
For those that enjoy a good algebra challenge, here's the other way to the solution. I like using algebra as often as possible because I have less of a chance to make a mistake, but for this problem, it's not the most straightforward application. Let P=the price above $10 for a ticket. We can then w...
- by VP_RedSoxFan
Thu Jul 31, 2008 7:31 am- Forum: Problem Solving
- Topic: Balcony theatre seats
- Replies: 5
- Views: 5571
I like the approach by acmeheadshot. If you run a quick chart of possible N and then the solutions to 2^N and N^2 you can a ) see that there are 2 (N=2,4) solutions for N, b ) that as N gets bigger 2^N and N^2 move farther apart so we can be reasonable sure there aren't more as N gets bigger, and c ...
- by VP_RedSoxFan
Thu Jul 31, 2008 7:15 am- Forum: Problem Solving
- Topic: 2^n=n^2
- Replies: 4
- Views: 3217
The standard approach for probability is to take the number of ways you can get your desired outcome divided by the total possible outcomes. In this case, our desired "outcome" is exactly 3 heads. Since we don't care what order we get them in we can use the combination formula 5_C_3. This ...
- by VP_RedSoxFan
Thu Jul 31, 2008 7:10 am- Forum: Problem Solving
- Topic: Coin Probabilty please help!
- Replies: 3
- Views: 2481
If there are 10 L of solution and 10% is nitric acid, then you can say that 1 L is acid and 9 L of water. To have 1 L of acid by 4% of the solution, then you set up this equation: 1L acid/xL solution = 4% Solve for x and you get 25 L of solution of which 1 L is acid and 24 L is water. 24 L - 9 L = 1...
- by VP_RedSoxFan
Thu Jul 31, 2008 7:02 am- Forum: Problem Solving
- Topic: Solution Problem
- Replies: 6
- Views: 5441
Working backwards, we can calculate that the $4000 in "American" prices was purchased in Italy by Bianca at 60% off, so $1,600 (don't confuse the discount amount with the actual cost here). The question says that Bianca sells them for 25% more than she paid, which would exactly equal her p...
- by VP_RedSoxFan
Tue Jun 03, 2008 1:49 pm- Forum: Problem Solving
- Topic: GMAT PS #2
- Replies: 3
- Views: 2968
The algebra here is pretty straightforward, I think, so stop me if I put up something crazy here:
Original sweatshirt price = x
Price of second, discounted sweatshirt = 0.75x
Therefore, since the two sweatshirts cost $175, we can write x + 0.75x = 175.
x = 100, Answer = [C]
- by VP_RedSoxFan
Tue Jun 03, 2008 1:36 pm- Forum: Problem Solving
- Topic: GMAT PS
- Replies: 5
- Views: 2545
I hope I'm not overstepping any bounds either, but I'd recommend taking a visit to some of the local prep courses and checking out their teachers. I'm convinced that aside from your own work ethic, the primary driver in a successful course is compatibility with the course instructor. Keep in mind, o...
- by VP_RedSoxFan
Tue Jun 03, 2008 1:22 pm- Forum: GMAT Strategy
- Topic: Suggestions on GMAT Prep Course Pls.
- Replies: 5
- Views: 1665
We're trying to find information about the line coming out of the origin and going to the midpoint between P and Q. In order to calculate the slope of a line is rise/run and since we're calculating the slope of a line coming out of the origin, the slope will simply be the y-coordinate/x-coordinate o...
- by VP_RedSoxFan
Tue Jun 03, 2008 1:11 pm- Forum: Problem Solving
- Topic: Slope
- Replies: 17
- Views: 7311
We can start by figuring out what each set looks like, as much as possible. A = {11,13,17,19,23} B = {5 even numbers} C = {5 consecutive multiples of 7} Since we're just comparing the standard deviations relative to each other, no need to whip out the big formula and try to calculate each Set's stde...
- by VP_RedSoxFan
Tue Jun 03, 2008 7:58 am- Forum: Problem Solving
- Topic: another stan dev problem
- Replies: 4
- Views: 2925