I noticed the following question in the Divisibility & Primes Advanced section: If x is a prime number, what is the value of x? (1) There are a total of 50 prime numbers between 2 and x, inclusive. (2) There is no integer n such that x is divisible by n and 1 < n < x. The answer in the str...

http://i41.tinypic.com/2vnrold.jpg 1. I understand how statement 1 is sufficient. Because, if c is negative, then a - b > 0 Thus, a > b SUFFICIENT 2. Isn't statement 2 also sufficient? I.e. a + b < 0 a < -b a > b SUFFICIENT? The answer in the guide is ( A ).

I was also going through the Advanced problem set on pg. 151 of the NP study guide (3rd edition), and stumbled upon the following data sufficiency question which I think raises a similar question: If x, y, and z are prime numbers and x < y < z, what is the value of x? (1) xy is even. (2) xz is...

Thanks Stacey. My mistake...I can't believe I forgot to divide both sides. I must have been on an off day when I first posted that message. Sorry about this!!

Thanks again Stacey.

Just to clarify:

Since a prime number is a number that is only divisible by 1 and itself, then this by definition excludes negative numbers, because there can only be 2 factors that make up the prime number?

How do we use the double matrix method for the following Data Sufficiency question below? How many people are directors of both charities A and B? (1) Charity A has 16 directors and Charity B has 9 directors. (2) 18 directors attended a joint meeting of the directors of Charity A and Charity B, and ...

Thanks Ron.

For statement 2, I had trouble putting the 0 in the middle square (i.e. NOT A and NOT B). I overlooked the clause 'and not one director was absent from the meeting', and was therefore unable to continue populating the matrix.

"In certain congested urban areas, commuters who use public transportation options such as trains and subways spend approximately 25 percent less time in transit, on average, to reach their destinations than commuters who opt instead to take cars to their destinations . Even individuals who dr...

I've always been able to see the trapezoid (I think), but I can't understand how AE is the height. To me, AB or DC look more like height (10).

Are there any other ways to look at it?

Thanks Emily.

What percent is x of y? (1) x = 3y (2) x - y = 6 I've always assumed that the word ' of ' meant ' times '. So when I saw this question I tried to rephrase the question stem to the following: z /100 = xy That is we need to know the value of x and y in order to figure out z . However, the answer expl...

Hi mgshorr, thanks for the reply. However...didn't you just change the question? I can understand how your solution would answer the question 'X is what percent of Y?'. But the question actually says 'What percent is X of Y?'. Aren't these two questions fundamentally different? Or is there something...

Hi Ron, I'm actually a native speaker (born and raised in Australia). If its any consolation, I'm a musician, so it could just be a non-native/musician problem. Regardless, I've discovered that I make fewer mistakes when I follow the literal rules, so I've made it a point to always convert the probl...

when u are asked: what % of 10 is 6 what do u do? I would make z the value we want to determine: z /100 x 10 = 6 z /10 = 6 z = 60 Therefore 60% of 10 is 6 what % is 6 of 10 ? would you say this is a different question and if so how would do it Yes, in my opinion it is a different question. z /100 =...

common sense tells me that when I have two numbers x and y and I know one is a % of the other(in other words one is a fraction of the other) , then the answer is always x/y * 100 or y/x* 100 ...... Unfortunately, my common sense is fallible. Consequently, I'd rather rely on a more foolproof method,...