Rastis wrote:GMATGuruNY,
How did you choose the numbers that you plugged in? I do not understand.
The problem offers messy numbers to test a basic number property rule.
To determine what rule is being tested, I plugged in easier numbers that follow the same pattern as the messy numbers given in the problem.
The basic question is this:
If a,b,c,d and e are positive integers such that a<b<c<d<e, which of the following is greatest?
A. (a+3)/a
B. (b+3)/b
C. (c+3)/c
D. (d+3)/d
E. (e+3)/e
Plugging in a=1, b=2, c=3, d=4, d=5 results in the following:
A: 4/1 = 4
B: 5/2 = 2.5
C: 6/3 = 2
D: 7/4 = 1.75
E: 8/5 = 1.6
The greatest answer choice is
A.
The easier numbers show the rule that is being tested:
If x<y<0 and c>0, then:
(x+c)/x > (y+c)/y
An alternate approach to the problem above would be to rewrite all of the answer choices in the form (x+c)/x:
A. 1876455/1876452
(1876452 + 3)/1876452
1 + 3/1876452
B. 1883449/1883446
(1883446 + 3)/1883446
1 + 3/1883446
C. 1883456/1883453
(1883453 + 3)/1883453
1 + 3/1883453
D. 1883459/1883456
(1883456 + 3)/1883456
1 + 3/1883456
E. 1883494/1883491
(1883491 + 3)/1883491
1 + 3/1883491
Comparing the answer choices:
The only difference is the fraction being added to 1.
Since the denominator increases as we proceed from A to E -- while the numerator stays the same -- the resulting fractions keep getting smaller.
Thus, the greatest answer choice is
A.
Here are two other problems in which I plugged in easier numbers in order to determine the number property rule being tested:
https://www.beatthegmat.com/og-12-proble ... 00085.html
https://www.beatthegmat.com/matdfhfg-t83392.html
Last edited by GMATGuruNY on Fri Jan 06, 2012 7:44 am, edited 1 time in total.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at
[email protected].
Student Review #1
Student Review #2
Student Review #3