4 math questions from GMATPrep exam

Hi everyone,

These are the four questions I got wrong...and for the life of me, I can't come up with the answer. Help, please?

1.) If 450y= n^3; which of the following is an integer?

I y/3x(2^2)x5

II y/(3^2)x2x5

III y/3x2x(5^2)

(A)None
(B) I only (correct answer)
(C) II only
(D) III only
(E) I, II & III
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2.) The perimeter of square S and rectange R are equal. Ratio of the sides of R are 2:3; what is the ratio of area of R to are of S?

(A) 25:16
(B) 24:25 (correct answer)
(C) 5:6
(D) 4:5
(E) 4:9
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3.) Line n and line p lie on the xy plane. Is the slope of line n less than slope of line p?

(1) n and p intersect at (5,1)
(2) y intercept of line n is greater than the y intercept of line p

Correct answer: (C): sufficient together
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4.) 6 senior officers and 4 junior officers -- out of these a committee of 3 seniors and 1 junior must be selected. How many different committees are possible?

(correct answer: 80)

I've pretty much given up on P&C, so I'm not worried about this one. I have one week left till my exam and I've accepted P&C as my weakness.



Any help with the above questions would be much appreciated! Please help.

Thanks,
R