TestMagic Forums - GMAT Data Sufficiency

Yet another GPrep DS

atishree — Fri, 20 Nov 2009 18:59:48 GMT

Please discuss

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GPrep DS doubt again

atishree — Fri, 20 Nov 2009 18:42:12 GMT

Please explain...

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GPrep DS 2

atishree — Fri, 20 Nov 2009 16:08:22 GMT

Please discuss

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Not that easy

atishree — Fri, 20 Nov 2009 16:01:34 GMT

Martha bought several pencils. If each pencil was either a 23-cent pencil or a 21-cent pencil, how many 23-cent pencil did martha buy?
(1) Martha bought a total of 6 pencil.
(2) The total value of pencils Martha bought was 130 cents.

GPrep DS doubt 1

atishree — Fri, 20 Nov 2009 13:53:23 GMT

Please discuss

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GPrep DS doubt

atishree — Fri, 20 Nov 2009 13:50:13 GMT

Please discuss

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GPrep DS

atishree — Fri, 20 Nov 2009 13:49:06 GMT

Please discuss

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GPrep DS1

atishree — Fri, 20 Nov 2009 13:47:43 GMT

Please discuss

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MODULE

marianha — Wed, 18 Nov 2009 17:55:06 GMT

If xyz ≠ 0, is x (y + z) ≥ 0?
(1) │y + z│ = │y│ + │z│
(2) │x + y│ = │x│ + │y│

oa

SPOILER: c

having hard time with modules , pls advice how to approach such questions

Basic Data Sufficiency - Though tricky

stantheman — Tue, 17 Nov 2009 17:35:54 GMT

What is ab?

(1) a/b = 2/3

(2) a^3 = 64 and b^3 = 216

I don't have the answer, but I am questioning if it is D or B. With (1), can we say that a = 2 and b = 3? I mean, a could = 4 and b could = 9, changing the value of ab. I need some reassurance here! Thanks.

Race question

atishree — Tue, 17 Nov 2009 16:33:07 GMT

Jen and Linda run a 120-yard race, where both of them maintains a constant speed in each half(60 yards) of the race. Also they increase their speeds after teh first half. If Jen covers the first half of the race at a constant speed of 4 yards/second and increases her speed to 5yards/second in the second half, what is Linda's speed in the first half?
(1)After 18 seconds of the race, Jen was ahead of Linda by 21 yards, who was still in the first half.
(2)Jen beats Linda in the race by 3 seconds.

Gprep-Equations

Fiver — Tue, 17 Nov 2009 14:46:54 GMT

PLease discuss

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Gprep-Remainder Theorem

Fiver — Tue, 17 Nov 2009 14:44:29 GMT

Please discuss.

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ETS_DS

farooq — Tue, 17 Nov 2009 12:28:42 GMT

1. While Mel is on disability leave, his employer pays him a monthly disability benefit equal to $1,200 plus 40 percent of the amount of his monthly salary in excess of $2,000. What is Mel�s monthly salary?

(1) Mel�s monthly disability benefit from his employer is $1,600.
(2) Mel�s monthly salary exceeds $2,500.

2. If car X followed car Y across a certain bridge that is 21mile long, how many seconds did it take car X to travel across the bridge?

(1) Car X drove onto the bridge exactly 3 seconds after car Y drove onto the bridge and drove off the bridge exactly 2 seconds after car Y drove off the bridge.
(2) Car Y traveled across the bridge at a constant speed of 30 miles per hour.

3. If n is a positive integer, what is the tens digit of n?

(1) The hundreds digit of 10n is 6.
(2) The tens digit of n + 1 is 7.

4. Is | x + 2 | < 3?
(1) x < 1
(2) x > -5

5. The figure above shows the number of meters in the lengths of the four sides of a jogging path. What is the total distance around the path?

(1) One of the sides of the path is 120 meters long.
(2) One of the sides of the path is twice as long as each of the two shortest sides.

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Factoring DS Problem

mymagic — Tue, 17 Nov 2009 01:01:06 GMT

If x and y are positive, does (x-2)(y-3) = 6?

(1) 3x = y(x-2)
(2) (x-8)((y^2) + 5) = 0

Data Sufficiency Answer choices A-E.

OA is A. Statement I alone is sufficient but statement II is not.

The explanation as listed foils the original equation provided in the question stem (x-2)(y-3) to yield xy-3x-2y+6 = 6. Similarly, statement I is multiplied out to yield xy-3x-2y = 0. So Statement I is sufficient. No problem there.

Statement II is where I get lost. The explanation goes that since x-8 is multiplied by y squared plus five, either one of these must be equal to zero since their product is zero. Understood. It goes on to say that y squared plus five cannot be zero because y squared is automatically positive and its added to five. So the explanation says that x-8 = 0 so x=8. X=8 is then substituted into (x-2)(y-3) = 6 to yield Y = 4. I'm fine up to here--but the explanation does not stop there. It goes on to say that if x = 8 and y is any other vaue than 4 ie y=5 then (x-2)(y-3) does not equal six and the answer is no. For this reason the question says that II is insufficient.

Essentially what I'm asking is why is statement II insufficient? Sorry for the wordy post....

Thanks :)