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Thanks everyone who contributed to this post. Pratyoosh. Q. At a certain university, the ration of the number of teaching assistants to the number of students in any course must always be greater than 3:80. At this university, what is the maximum number of students possible in a course that has 5 te...

by pratyoosh

Mon Nov 29, 2010 1:42 pm
Forum: Problem Solving
Topic: GMAT Prep problem.
Replies: 8
Views: 2056

Agreed. I have noticed its the silly mistakes where I am getting caught out more often, and need to work on it. Thanks for your help once again. Thanks for the explanation Geva, I followed the first approach but must have made a mistake with the inequality sign (substituted '<' for '=') and hence en...

by pratyoosh

Mon Nov 29, 2010 12:51 am
Forum: Problem Solving
Topic: Probability Q
Replies: 6
Views: 1534

Got it, I lost the problem with the "and" / "or" condition and ended up using either increments of 0.3 or doubling it up. Thanks. Just follow the terms of the question, one day at a time: 1st day: fine is $0.1 2nd day: either raise by 0.3 to get 0.1+0.3=$0.4 OR double the fine to...

by pratyoosh

Mon Nov 29, 2010 12:41 am
Forum: Problem Solving
Topic: Word problem.
Replies: 2
Views: 933

Thanks Geva, but a question for you - in such problems, do we not try and resolve the inequality first ? If we just go with the base equation and resolve it, we get x ^ 0 which equals 1. Am I reading it correct? C seems the obvious answer, bt if that were the were teh case, then this question would ...

by pratyoosh

Mon Nov 29, 2010 12:39 am
Forum: Problem Solving
Topic: Inequality
Replies: 5
Views: 1442

Thanks for the explanation Geva, I followed the first approach but must have made a mistake with the inequality sign (substituted '<' for '=') and hence ended up with 18 ! Alternative approach: reverse Plug in the answer choices. Each of the five answer choices is a possible number of yellow balls. ...

by pratyoosh

Mon Nov 29, 2010 12:37 am
Forum: Problem Solving
Topic: Probability Q
Replies: 6
Views: 1534

Thanks for the explanation Geva. the graph intersects the x axis when y=0. So the question is asking "when is (x+a)(x+b)=0?" It's a factored formula. the product will equal 0 when either one of the factors equal 0, i.e. either x+a=0 (so x=-a) OR when x+b=0 (so x=-b) Thus, to answer the que...

by pratyoosh

Mon Nov 29, 2010 12:20 am
Forum: Data Sufficiency
Topic: Coordinate Geometry Q - DS
Replies: 2
Views: 1193

Word problem.

Q. A certain library assess fines for overdue books as follows. On the first day that a book was overdue, the total fine is $0.10. For each additional day that the book is overdue, the total fine is either increased by $0.30 or doubled, whichever results in the lesser amount. What is the total fine ...

by pratyoosh

Mon Nov 29, 2010 12:09 am
Forum: Problem Solving
Topic: Word problem.
Replies: 2
Views: 933

Probability Q

Q. From a bag containing 12 identical blue balls, y identical yellow balls, and no other balls, one ball will be removed at random. If the probability is less than 2/5 that the ball removed will be blue, what is the least number of yellow balls that must be in the bag? A. 17 B. 18 C. 19 D. 20 E. 21 ...

by pratyoosh

Mon Nov 29, 2010 12:07 am
Forum: Problem Solving
Topic: Probability Q
Replies: 6
Views: 1534

Coordinate Geometry Q - DS

Q. In the xy-plane, at what two points does the graph of y = (x + a)(x + b) intersect the x-axis?

1. a + b = -1
2. The graph intersects the y-axis at (0, -6).

Ans: C

by pratyoosh

Mon Nov 29, 2010 12:05 am
Forum: Data Sufficiency
Topic: Coordinate Geometry Q - DS
Replies: 2
Views: 1193

Functions

Q. For which of the following functions f(x) = f(1 - x) for all x?

A. f(x) = 1 - x
B. f(x) = 1 - x^2
C. f(x) = X^2 - (1 - x^2)
D. f(x) = x^2 (1 - x)^2
E. f(x) = x / (1 - x)

Ans: D

by pratyoosh

Mon Nov 29, 2010 12:03 am
Forum: Problem Solving
Topic: Functions
Replies: 2
Views: 885

Inequality

Q. If x != 0, then [ sqrt(x^2) ] / x =

A. -1
B. 0
C. 1
D. x
E. |X| / x

Ans: E[/list]

by pratyoosh

Mon Nov 29, 2010 12:00 am
Forum: Problem Solving
Topic: Inequality
Replies: 5
Views: 1442

Brilliant, thanks Rahul. Lindsay can paint 1/x part of a certain room in 20 minutes. So in 1 hour = 60 minutes, he can paint 3/x part of a certain room. Since Lindsay and Joseph combined can paint the whole room in 1 hour, part of room painted by Joseph in 1 hour is 1 – 3/x = (x-3)/x. So part of r...

by pratyoosh

Sun Nov 28, 2010 11:56 pm
Forum: Problem Solving
Topic: Work rate problem - 2
Replies: 4
Views: 1212

Hmmmm.. Understood. Thanks. pratyoosh wrote: I c. Had got 133.something as the answer, but I choose 134 as it said "maximum number of students" and presumed that since I had the decimals there, that 134 would be the safer bet! Thanks for your help. Pratyoosh, the answer as Shovan described...

by pratyoosh

Sun Nov 28, 2010 11:54 pm
Forum: Problem Solving
Topic: GMAT Prep problem.
Replies: 8
Views: 2056

Work rate problem - 2

Q. Lindsay can paint 1/x of a certain room in 20 minutes. What fraction of the same room can Joseph paint in 20
minutes if the two of them can paint the room in an hour, working together at their respective rates?
A. 1/3x
B. 3x/(x – 3)
C. (x – 3) / 3x
D. x / (x – 3)
E. (x – 3) / x

A: C

by pratyoosh

Sun Nov 28, 2010 1:59 pm
Forum: Problem Solving
Topic: Work rate problem - 2
Replies: 4
Views: 1212

Work rate problem

Q. Pumps A, B and C operate at their respective constant rates. Pumps A and B, operating simultaneously, can fill a certain tank in 6/5 hours; Pumps A and C, operating simultaneously, can fill the tank in 3/2 hours; And pumps B and C, operating simultaneously, can fill the tank in 2 hours. How many ...

by pratyoosh

Sun Nov 28, 2010 1:17 pm
Forum: Problem Solving
Topic: Work rate problem
Replies: 3
Views: 1479