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30sec
B it is
a/b*c/d = b/c*a/d
All we need to know is for a to be greater than d to create a larger product than b/c on the other side of the inequality. B gives that away _________________

Whithout using any number, what you get from the stem is (a/b) (c/d)
in another way it is equal to a/d . c/b so greater than c/b if a/d > 1
That is exactly the purpose of second statement.

Thanks twixt. I still haven't got it. a/d has to greater than 1 provided b/c is not very small. Say if b/c is 0.001 and c/b is 1000, then does B alone anaswer the Q. so if a/d is 5 then, 5*0.001>1000 which is not true. If we reverse it, it becomes 5*1000>0.001. whic is true. So I am not sure if B alone can answer.
Plz bear with me as i am really not getting it.
S

Thanks twixt. I still haven't got it. a/d has to greater than 1 provided b/c is not very small. Say if b/c is 0.001 and c/b is 1000, then does B alone anaswer the Q. so if a/d is 5 then, 5*0.001>1000 which is not true. If we reverse it, it becomes 5*1000>0.001. whic is true. So I am not sure if B alone can answer. Plz bear with me as i am really not getting it. S

I am not sure what do you try to say here. The question does not ask you whether (a/b) x (c/d) > (b/c), unless you typed it wrong in the first place.

Re: If a, b, c, and d are positive integers, is (a/b) (c/d) > c/ [#permalink]
21 Mar 2013, 03:40

Expert's post

If a, b, c, and d are positive integers, is (a/b) (c/d) > c/b?

Is \frac{a}{b}*\frac{c}{d}>\frac{c}{b}? --> is \frac{c}{b}*\frac{a}{d}>\frac{c}{b}? --> since all variables are positive, then we can safely reduce by c/b: is \frac{a}{d}>1? --> cross-multiply: is a>d?

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