Uva@90 wrote:
Hi GMATGuruNY,
I have one doubt regarding the rounding up. In question they mentioned E is obtained by
Each decimal in T whose tenths digit is even is rounded up to the nearest integer, and each decimal in T whose tenths digit is odd is rounded down to the nearest integer; E is the sum of the resulting integers.
But in your solution you have obtained S by rounding up
To minimize S, we must ROUND UP the even decimals as MUCH as possible (from .2 to the next highest integer) and ROUND DOWN the odd decimals as LITTLE as possible (from .1 to the next smallest integer).
Let S = 10(.2) + 20(.1) = 4.
In E, .2 is rounded up to 1 and .1 is rounded down to 0:
E = 10(1) + 20(0) = 10.
Thus, the MAXIMUM possible value of E-S = 10-4 = 6.
Could you explain why you did like this ?
Correct me if I am wrong.
Regards,
Uva
10 of the values must have an EVEN tenths digit:
0.2, 0.4, 0.6. or 0.8.
(Since we're considering decimals only up to the tenths place, I've excluded 0.0, which is an integer value.)
10 the values must have an ODD tenths digit:
0,1, 0.3., 0.5. 0.7, or 0.9.
When E-S is maximized and minimized, the value of E -- the ESTIMATED sum -- will be the same in each case.
The 10 even decimals will be rounded UP to 1, while the 20 odd decimals will be rounded DOWN to 0, yielding the following sum:
E = 10(1) + 20(0) = 10.
To MAXIMIZE the value of E-S, we must MINIMIZE the value of S -- the ACTUAL sum of the decimals.
To minimize the value of S, we must use the SMALLEST decimal in each list.
The smallest value in the first list is the even decimal that is rounded up the MOST:
0.2.
The smallest value in the second list is the odd decimal that is rounded down the LEAST:
0.1.
Thus:
Least possible value of S = 10(.2) + 20(.1) = 4.
Thus:
Maximum value of E-S = 10-4 = 6.
To MINIMIZE the value of E-S, we must MAXIMIZE the value of S -- the ACTUAL sum of the decimals.
To maximize the value of S, we must use the GREATEST decimal in each list.
The greatest value in the first list is the even decimal that is rounded up the LEAST:
0.8.
The greatest value in the second list is the odd decimal that is rounded down the MOST:
0.9.
Thus:
Greatest possible value of S = 10(.8) + 20(.9) = 26.
Thus:
Minimum value of E-S = 10-26 = -16.
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
