If z is an odd integer, is 300z>1500?

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If z is an odd integer, is 300z>1500?

by gmat_guy666 » Thu Aug 28, 2014 10:52 am
If z is an odd integer, is 300z>1500?

A) 0<√z<8
B) 1<z^2<45

OA B

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by GMATGuruNY » Thu Aug 28, 2014 11:04 am
gmat_guy666 wrote:If z is an odd integer, is 300z>1500?

A) 0<√z<8
B) 1<z^2<45

OA B
Dividing each side of 300z > 1500 by 300, we get:
z > 5.
Since z must be odd, the question stem can be rephrased as follows:
If z is odd, is z ≥ 7?

Statement 1: 0<√z<8
Squaring the inequality, we get:
0 < z < 64.
If z=3, then z is not an odd integer such that z ≥ 7.
If z=9, then z is an odd integer such that z ≥ 7.
INSUFFICIENT.

Statement 2: 1<z²<45
Here, it's not possible that z≥7, since 7²=49.
Thus, it must be true that z is NOT an odd integer such that z≥7.
SUFFICIENT.

The correct answer is B.
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by samjammin » Thu Aug 28, 2014 11:08 pm
Hi Folks,

What if in b: Z^2 is 25?
It would make Z=+/-5; so wouldn't it be ambiguous
300z= -1500(less than 1500),and 1500..

I'm really confused, can someone help. :(

Thanks,
samjammin

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by GMATGuruNY » Fri Aug 29, 2014 6:15 am
samjammin wrote:Hi Folks,

What if in b: Z^2 is 25?
It would make Z=+/-5; so wouldn't it be ambiguous
300z= -1500(less than 1500),and 1500..

I'm really confused, can someone help. :(

Thanks,
samjammin
Question stem: Is 3z > 1500?

If z=5, then the answer to the question stem is NO:
Is 300*5 > 1500?
NO.

If z=-5, then the answer to the question stem is still NO:
Is (300)(-5) > 1500?
NO.

When any value that satisfies statement 2 is plugged into the question stem, the answer in every case will be NO.
Thus, statement 2 is SUFFICIENT.
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by GMATinsight » Sat Aug 30, 2014 3:41 am
gmat_guy666 wrote:If z is an odd integer, is 300z>1500?

A) 0<√z<8
B) 1<z^2<45

OA B
FOR THE GIVEN QUESTION ANSWER MUST BE OPTION E
If the question is changed as Mitch suggested [Is z<7?]then answer should be Option B
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