Search found 13 matches
- by TuanNguyen87
Thu Jun 09, 2011 12:27 am- Forum: Problem Solving
- Topic: Reciprocals
- Replies: 9
- Views: 2810
Wow you're so smart and quickFrankenstein wrote:Hi,
(1/r) = (1/x)+(1/y) = (x+y)/xy
So, r = xy(x+y)
Hence, D
But can you explain for me more about reciprocals? I have no idea about this. Thanks so much!!!!
- by TuanNguyen87
Thu Jun 09, 2011 12:26 am- Forum: Problem Solving
- Topic: Reciprocals
- Replies: 9
- Views: 2810
Reciprocals
In an electric circuit, two resistors with resistances x and y are connected in parallel. In this case, if r is the combined resistance of these two resistors, then the reciprocal of r is equal to the sum of the reciprocals of x and y. What is r in terms of x and y? A. xy B. x + y C. 1/(x+y) D. xy/(...
- by TuanNguyen87
Thu Jun 09, 2011 12:21 am- Forum: Problem Solving
- Topic: Reciprocals
- Replies: 9
- Views: 2810
The probability
A certain junior class has 1,000 students and a certain senior class has 800 students. Among these students, there are 60 sibling pairs, each consisting of 1 junior and 1 senior. If 1 student is to be selected at random from each class, what is the propability that the 2 students will be a sibling p...
- by TuanNguyen87
Wed Jun 08, 2011 4:57 pm- Forum: Problem Solving
- Topic: The probability
- Replies: 8
- Views: 1941
- by TuanNguyen87
Wed Jun 08, 2011 2:35 pm- Forum: Problem Solving
- Topic: Good Question
- Replies: 7
- Views: 1291
Two vessels A and B contain milk and water mixed in the ratio 5:2 and 8:5 respectively. Find the ratio in which these mixtures are to be mixed to get a new mixture containing milk and water in the ratio 9:4. A] 5:2 B] 3:4 C] 2:5 D] 7:2 E] 2:9 OA later... Fraction of milk in A = 5/7 = 65/91. Fractio...
- by TuanNguyen87
Wed Jun 08, 2011 2:27 pm- Forum: Problem Solving
- Topic: Mixture sum 2
- Replies: 9
- Views: 8120
Probability
The probability is 1/2 that a certain coin will turn up heads on any given toss. If the coin is to be tossed three times, what is the probability that on at least one of the tosses the coin will turn up tails?
A. 1/8
B. 1/2
C. 3/4
D. 7/8
E. 15/16
Thanks a lot everyone!
Answer: D
- by TuanNguyen87
Mon Jun 06, 2011 10:50 pm- Forum: Problem Solving
- Topic: Probability
- Replies: 4
- Views: 1107
Call X total rooms => rented rooms = 3X/4 => not rented rooms = X/4
Then, we have AC rooms: 3X/5 => rented rooms with AC: (2/3)*(3X/5) = 2X/5
Thus, we have not rented rooms with AC: 3X/5 - 2X/5 = X/5
As a result, (X/5)/(X/4) = 0.8 = 80%
Answer: E
Hope it's useful 
- by TuanNguyen87
Mon Jun 06, 2011 5:17 pm- Forum: Problem Solving
- Topic: Set problem
- Replies: 7
- Views: 1650
Applicants
Of 30 applicants for a job, 14 had at least 4 years' experience, 18 had degrees, and 3 had less than 4 years' experience and did not have a degree. How many of the applicants had at least 4 years experience and a degree?
A. 14
B. 13
C. 9
D. 7
E. 5
Thanks very much guys!
Answer: E
- by TuanNguyen87
Mon Jun 06, 2011 4:51 pm- Forum: Problem Solving
- Topic: Applicants
- Replies: 3
- Views: 2004
Because the area of ABCD is 25, so each side is 5. Then call the larger sides are a; the smaller sides are b And call x is the area of the smaller one => the area of the larger is 9x Therefore, we have: a^2= 9x => a b^2= x => b => a + b= 5 => we have x => finally, we figure out b= 5/4 IMO B
- by TuanNguyen87
Mon Jun 06, 2011 12:22 am- Forum: Problem Solving
- Topic: Square
- Replies: 12
- Views: 4074
I think we just need to replace x by 1.5 and because 1.5 > 0. Thus,
f(1.5)= |1.5| + |1.5 - 2|= 1.5 + (2 - 1.5)= 2 
- by TuanNguyen87
Sun Jun 05, 2011 8:48 pm- Forum: Problem Solving
- Topic: Function
- Replies: 13
- Views: 1541
I'm sorry that I forgot to write the answer choices:
A. 2N/15
B. 3N/5
C. 5N/3
D. 5N/2
E. 15N/2
Yeah the correct one is D. 5N/2
Thanks a lot Cans
- by TuanNguyen87
Sun Jun 05, 2011 12:23 pm- Forum: Problem Solving
- Topic: In terms of
- Replies: 4
- Views: 1243
In terms of
Q. 124, pg. 168, GMAT The Official Guide 11th Edition: According to a car dealer's sales report, 1/3 of the cars sold during a certain period were sedans and 1/5 of the other cars sold were station wagons. If N station wagons were sold during the period, how many sedans, in terms of N, were sold? I ...
- by TuanNguyen87
Sun Jun 05, 2011 9:36 am- Forum: Problem Solving
- Topic: In terms of
- Replies: 4
- Views: 1243