Search found 7 matches
- by betamax
Sun Feb 08, 2009 12:22 pm- Forum: Problem Solving
- Topic: GMAT Pre Questions ---Probability
- Replies: 5
- Views: 4585
I go with a. 13c1*13c1*13c1*13c1 * 48c1 *47c1 Once you have the 4 suits, the remaining 2 cards don't matter. You just need at least 1 of each suit. Each other card thereafter then just increases the number of any of the 4 suits you already have. So you choose the next card of the remaining 48 and th...
- by betamax
Sat Feb 07, 2009 11:51 pm- Forum: Problem Solving
- Topic: Telling permutation problems from combinations problems
- Replies: 4
- Views: 2277
Re: combination or permutation?
A group of 8 friends want to play double tennis. How many different ways can the group be divided into 4 teams of 2 people? Logic thinking: 1st group: C(2,8); 2nd group: C(2,6); 3rd group: C(2,4) and 4th group: C(2,2). So the total combination is: C(2,8)*C(2,6)*C(2,4)*C(2,2) = 2,520 Is it correct? ...
- by betamax
Fri Feb 06, 2009 10:01 am- Forum: Problem Solving
- Topic: combination or permutation?
- Replies: 3
- Views: 1436
Re: Advanced Exponent Techniques Online?
Hi everyone. I was wondering if there was an online source for advanced exponents? For example, I never knew that 3^2x=3^8 could be solved for x by getting rid of the 3's and making it 2x=8, or that 3^(4x+2) can be rewritten as 9^(2x+1). I see examples like these on these forums and in the quantita...
- by betamax
Thu Feb 05, 2009 11:53 pm- Forum: GMAT Math
- Topic: Advanced Exponent Techniques Online?
- Replies: 1
- Views: 1996
Re: integers
If 10^50 – 74 is written as an integer in base 10 notation, what is the sum of the digits in that integer? A. 424 B. 433 C. 440 D. 449 E. 467 10^50 -74= 9*10^49+9*10^48+9*10^47....2*10^1+6*10^0... basically 99999999999999999....99999926 <-------48 9's followed by a 2 and a 6 9*48+2+6=440 For this p...
- by betamax
Thu Feb 05, 2009 11:06 pm- Forum: Problem Solving
- Topic: integers
- Replies: 2
- Views: 2073
Re: Probability..help
There are 11 women and 9 men in a certain club. If the club is to select a committee of 2 women and 2 men, how many different such committees are possible? A. 120 B. 720 C. 1,060 D. 1,520 E. 1,980 There are a total of 11!/2!(11-2)! * 9!/2!(9-2)! = 1980 11!/2!9! = 11*10*9!/2!9!=11*10/2 9!/2!7!=9*8*7...
- by betamax
Thu Feb 05, 2009 10:33 pm- Forum: Problem Solving
- Topic: Probability..help
- Replies: 3
- Views: 6125
Re: a probability problem, who can help? Thanks!
If the probability of rain on any given day in city x is 50%, what is the probability if with rain on exactly 3 days in a five day period? For this problem you need to use the binomial distribution formula or you can lay every possible outcome out: R=Rain N=No rain so your possible outcomes are RRR...
- by betamax
Thu Feb 05, 2009 9:27 pm- Forum: Problem Solving
- Topic: a probability problem, who can help? Thanks!
- Replies: 4
- Views: 2698