Search found 199 matches
I do not understand your last step: If Model #6 and Model #4 are selected, but Model #5 is not, why is this 4C3? Is it because there are 4 models left and three of them have to be choosen in order to have a total of 5 models selected? Yes, 4 left off of 7: 4 and 6 are pre-selected, we dont wanna se...
- by palvarez
Mon Nov 30, 2009 11:49 am- Forum: Problem Solving
- Topic: probability problem with condition
- Replies: 4
- Views: 1591
For any two positive integers x and y: xy = (GCF of x and y) X (LCM of x and y) In this case, it would be 10 X 180 = 1800 so C is the answer. Where this rule come from? could you please explain this rule by a simple example of two integers? it is a simple proof, but hard to type here. Check here ht...
- by palvarez
Wed Nov 25, 2009 2:40 pm- Forum: Data Sufficiency
- Topic: GCF / LCM DS Problem
- Replies: 6
- Views: 3336
Rephrase it
Is a^2 - b^2 > 0
or (a+b)(a-b) > 0
1. a+b < 0, insufficient, since we need to know if a - b > 0
2. a < 0, insufficient.
Both insufficient, since we can't say b < 0. However, if (1) would have been b < a, the answer wud be C.
- by palvarez
Wed Nov 25, 2009 1:37 pm- Forum: Data Sufficiency
- Topic: Absolute Value
- Replies: 4
- Views: 1438
IMO : B overall you should know that every number from 0-9, has recurring format of unit digit when multiplied by itself. for eg: 3^1 = 3 <-- unit digit of mulplication 3^2 = 9 3^3 = 7 3^4 = 1 3^5 = 3 similarly... 9 7 1 3 9 7 3 1... so over all we are only interested to know the unit digit of 'a'. ...
- by palvarez
Wed Nov 25, 2009 1:28 pm- Forum: Data Sufficiency
- Topic: Unit Digit
- Replies: 4
- Views: 2373
Q. What is the units digit of a^36? a) a^2 has 9 as the units digit b) a^3 has 3 as the units digit Rephrase What is a^36 (mod 10) (a) a^2 (mod 10) = 9 (b) a^3 (mod 10) = 3 a. a^2 = 9 (mod 10); a^36 (mod 10) = 9^18 (mod 10) = (-1)^18 = 1 Sufficient 2. a^3 = 3 (mod 10); a^36 (mod 10) = 3^12 (mod 10)...
- by palvarez
Wed Nov 25, 2009 1:26 pm- Forum: Data Sufficiency
- Topic: Unit Digit
- Replies: 4
- Views: 2373
I always get stuck on these type of question. When i look at the explanation it seems simple enough but just can't figure it out.Does anyone have a quick way to solve this type of question which may have variations such as: -Sum of all even numbers from 1 to 199 -sum of all odd number from 100 to 3...
- by palvarez
Wed Nov 25, 2009 1:22 pm- Forum: GMAT Math
- Topic: sum of all even numbers from 99 to 301
- Replies: 19
- Views: 80383
i always get confused in this q: solution is 90% glycerin . I f there are 4 gallons of solution then how much water in gallons must be added to make a 75% glycerin solution a)1.8 b)1.4 c)1.2 d) 1.o e) 0.8 The tricky part: translating water as 0 percent glycerin. Once ya get it right, everything goe...
- by palvarez
Wed Nov 25, 2009 1:20 pm- Forum: Problem Solving
- Topic: plz answer this mixture problem
- Replies: 8
- Views: 2817
(1) 10,000(1+.25r)^n - 10,000*.25r*n = 18. We are left with a equation with two unknowns.
(2) Insufficient.
Combined: we know about n, so we can figure out r. Sufficient.
C
- by palvarez
Sat Nov 21, 2009 12:04 pm- Forum: Data Sufficiency
- Topic: SIMPLE AND COMPOUND INTEREST COMBINED!!!
- Replies: 1
- Views: 1183
|a| = |-a|
1. -M = |M|, therefore M<=0. Insufficient, since M can be 0
2. M = 3 or -3. Insufficient.
Combined, M = -3. Sufficient.
C is the answer
- by palvarez
Sat Nov 21, 2009 12:01 pm- Forum: Data Sufficiency
- Topic: Strong concept tested: Please help me out
- Replies: 3
- Views: 1096
- by palvarez
Sat Nov 21, 2009 11:54 am- Forum: Problem Solving
- Topic: A Scale and Intensity
- Replies: 2
- Views: 1059
Incomplete. What do you want to find?
a), b) and c) can have some value only when x <= 2
d) and e) are defined when x >= 2
a > c > b since x <=2
d > e, since x >= 2
- by palvarez
Sat Nov 21, 2009 10:45 am- Forum: Problem Solving
- Topic: inequalities
- Replies: 1
- Views: 1040
a/b = 2/3 is same as a = 2k and b = 3k. You can transform two unknowns into one unknown.
TV1:
d^2 = l^2 + b^2
30^2 = k^2 + 4k^2
k^2 = 30^2/5
TV2:
30^2 = 9m^2 +16m^2
m^2 = 30^2/25
Find Area of TV2/Area of TV1
= (3m)(4m)/[k(2k)] = 6m^2/k^2 = 6(5)/25 = 6/5
Answer = 5/6 = 83/100
- by palvarez
Sat Nov 21, 2009 10:30 am- Forum: Problem Solving
- Topic: TV areas
- Replies: 4
- Views: 1339
1. angle ABC = 30; therefore, arc AC = 60 degrees. From this, we can conclude AC = radius
Computing the area of triangle requires: 2 sides, and the angle between those two sides. Insufficient
2. Circumference = 18. Diameter = 18/(3.14) < 6
A bad question written by wannabes!
- by palvarez
Sat Nov 21, 2009 1:18 am- Forum: Data Sufficiency
- Topic: triangle
- Replies: 7
- Views: 1346
75 175
equilibrium point is: 100
whats the distance between 75 and 100 = 25
whats the distance between 100 and 175 = 75
75% of 75 and 25 % of 175 is the answer.
3 of 75 and 1 of 175
225/(400) is the answer
- by palvarez
Sat Nov 21, 2009 1:06 am- Forum: Problem Solving
- Topic: Different Price Levels - Ratio problem (sort of)
- Replies: 3
- Views: 1124
Don't waste your money on buying books. Think of that problem as a weight balance problem in physics: another way of loking at the issue. Average is equilibrium. Weight*length = constant w1*l1 = w2*l2 l1 = 5 -2 =3 l2 = 10 -5 = 5 3*y = 5*x x: y = 3:5 Alligation rule is used heavily in pharmacy classe...
- by palvarez
Sat Nov 21, 2009 12:59 am- Forum: Data Sufficiency
- Topic: % Mixture Problem
- Replies: 5
- Views: 6964