Search found 19 matches
Re: PROBALITY
3 ways as shown above. Now, C1 & C2 can be arranged in 2 ways. Similarly B1 & B2 can be arranged in 2 ways. So, totally, the number of ways that the couples can sit together is = 2*2*3* = 12 ways The number of ways both the couples & the single can be seated is = 5!/(2!*2!) = 30 ways. S...
- by g2000
Mon May 04, 2009 8:42 am- Forum: Problem Solving
- Topic: PROBALITY
- Replies: 4
- Views: 1101
2 + 2 + 2^2 + 2^3 + 2^4 + 2^5 + 2^6 + 2^7 + 2^8 = 1 + (1 + 2 + 2^2 + 2^3 + ... + 2^8) = 1 + (2^0 + 2^1 + 2^2 + 2^3 + ... + 2^8) the portion (2^0 + 2^1 + 2^2 + 2^3 + ... + 2^8) take the 1st 2 terms 2^0 + 2^1 = 1 + 2 = 3 it's identical to 2^2 - 1 therefore, 2^0 + 2^1 + ... + 2^8 = 2^9 - 1 If we add th...
- by g2000
Mon May 04, 2009 6:21 am- Forum: Problem Solving
- Topic: pattern
- Replies: 3
- Views: 1243
area of rectangle = 100 if one side is x --> the other side is 100/x -> perimeter == 2 ( x + 100/x ) if (perimeter == circumference) 2 (x + 100/x) = 2 * pi * r pi * r = (x + 100/x) r = (x + 100/x) * 1/pi Area of circle = pi * r^2 = pi * ((x + 100/x) * 1/pi ) ^ 2 = 1/pi (x + 100/x) ^ 2
- by g2000
Mon May 04, 2009 6:15 am- Forum: Problem Solving
- Topic: rectangle
- Replies: 2
- Views: 1166
We have container A, B, C and D. Before, they have m balls. Let x be the # balls taken: y be the total # of balls b4 after A m y/16 B m 6y/16 C m 5y/16 D m 4y/16 For container A, m-x = y/16 y= total of all balls = 4m m-x = 4m/16 x = m-m/4 = 3/4m answer is C
- by g2000
Mon May 04, 2009 6:02 am- Forum: Problem Solving
- Topic: balls
- Replies: 2
- Views: 1327
- by g2000
Sun May 03, 2009 6:04 am- Forum: GMAT Strategy
- Topic: 99 level 700 questions from GMATPrep
- Replies: 55
- Views: 13706
combination problem
Given 7 people(A,B...G), we don't care if A is chosen first or last.
We have to eliminate those redundancies. How many of those? 2.
The equation is (if order matters)
7!/(7-2)! = 7! / 5!
If order matters not(our case), we have to divide by 2 (pair)
7! / ( (7-2)! * 2) = 7! /(5! * 2) = 7*6 / 2 = 21
- by g2000
Thu Apr 30, 2009 6:55 am- Forum: Problem Solving
- Topic: Why to divide by 2?
- Replies: 4
- Views: 4066
Isn't that C?
10^23 *2
I'm just curious the number of zeroes. It seems it's 23 zeroes, doesn'it?
If multiply by 2, that only changes the coefficient of 10^23.
For instance,
10^2 * 5
= 100 * 5
= 500
That's not 5000!?! (the extra mysterious one!?!)
- by g2000
Wed Apr 29, 2009 4:58 pm- Forum: Problem Solving
- Topic: How many digits does the product contain?
- Replies: 5
- Views: 1412
My approach is slightly different.
P(xy is even) = 1 - P(xy is odd)
In order to get odd for xy, both x and y need to be odd.
P(x is odd) = 1/2
P(y is odd) = 2/3
P(xy is odd) = 1/2 * 2/3 = 1/3
P(xy is even) = 1 - P(xy is odd)
= 1 - 1/3
= 2/3
- by g2000
Mon Apr 27, 2009 9:28 am- Forum: Problem Solving
- Topic: probability: even xy
- Replies: 5
- Views: 1449
the phrase
the resulting increase in ultraviolet radiation
have 2 consequences
1. endanger human health, causing a rise in the incidence of skin cancer and eye disease
2. perhaps even threatening global ecological systems
obviously, the tense of the 2nd one follows the 1st one.
- by g2000
Thu Apr 16, 2009 4:06 pm- Forum: Sentence Correction
- Topic: if industrial
- Replies: 4
- Views: 1463
factorization
As Feep mentioned, it's a factorization problem. First, factorize 147000 and you get the following 147000 = 2*2*2 * 3 * 5*5*5 * 7*7 The problem says the product of the points is equivalent of 147000. Therefore what we need to do is to count the number of 7. In our case, it is 2(because there are 2 s...
- by g2000
Mon Apr 13, 2009 7:32 pm- Forum: Problem Solving
- Topic: Official Guide Problem 234
- Replies: 5
- Views: 1399
how about A?
The question asks for a choice that undermines the conclusion. The conclusion says unionization does not raise women’s wages.
A.) my answer !
B.) too abstract and cannot draw a conclusion about unionization
C.) irrelevant
D.) result of the conclusion
E.) not talking about wage
- by g2000
Tue Sep 04, 2007 10:02 am- Forum: Critical Reasoning
- Topic: 1000 CR TEST III Q 15
- Replies: 5
- Views: 3147
E?
My reasoning is as follows: If each ticket has 50% chance of win, then the probability the first one wins is 50% and so its the second one. The probability that no one wins is as follows: first one does not win AND second one does not win 1/2 * 1/2 = 1/4 And the probability that at least one wins is...
- by g2000
Thu Aug 09, 2007 9:15 am- Forum: Problem Solving
- Topic: PS: Prob
- Replies: 3
- Views: 1960
B?
Is B more appropriate?
C, D and E are similar. Their conclusions are made according to the statistics. The comment by Dr. A is suggesting he refutes the validity of the medical report.
- by g2000
Thu Aug 09, 2007 8:53 am- Forum: Critical Reasoning
- Topic: CR 1000
- Replies: 8
- Views: 3581
2
For the question 1, I get square root of 208. I don't know why.... It seems like a triangle... For Question 2. Displacement = speed * time Let s be speed, s * 0.5 sec = 20 ft s = 20/0.5 ft/sec 20/0.5 ft/sec = (20 * 1/5280) / 0.5 mi/sec = (20 * 1/5280) / 0.5 * 60*60 mi/hr = (20 / 5280) * (60^2) / 0.5...
- by g2000
Thu Jan 25, 2007 10:57 am- Forum: Problem Solving
- Topic: DS
- Replies: 3
- Views: 3181
demand curve?
According to your description...Quantity for sale 100 200 98 204 96 206 To me, it is similar to a demand curve, namely a down slope graph. Next find the equation of this graph. (y - 100) / (x - 200) = (100 - 98 ) / (200 - 204) 2y - 200 = - (x - 200) y = - x / 2 + 200 This is just the graph that show...
- by g2000
Mon Jan 22, 2007 8:16 pm- Forum: Problem Solving
- Topic: Difficult Math Problem #89 - Algebra
- Replies: 6
- Views: 2469