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If y is an integer, is 3^y/10000 > 1

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If y is an integer, is 3^y/10000 > 1  [#permalink]

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New post Updated on: 27 Mar 2019, 23:04
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If y is an integer, is 3^y/10000 > 1?

1. 100/3^y < 0.01

2.\(\sqrt{3y} = 243\)



Statement 1 edited. Inconvenience regretted. It was not 10^y but 3^y.

Thank you.

Source : Barron's GMAT

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Originally posted by AkshdeepS on 27 Mar 2019, 01:43.
Last edited by AkshdeepS on 27 Mar 2019, 23:04, edited 5 times in total.
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Re: If y is an integer, is 3^y/10000 > 1  [#permalink]

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New post 27 Mar 2019, 05:35
Can anyone explain me how statement 1 is sufficient....

From statement 1 it's clear that y >= 5

If y is 5 , then answer to the main question is no..

If y is 9 , then the answer to the main question is yes...

Am I missing something???

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Re: If y is an integer, is 3^y/10000 > 1  [#permalink]

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New post 27 Mar 2019, 07:09
is the power of 3 from d questn (y/10000)? or the whole of 3^y) / 10000?

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Re: If y is an integer, is 3^y/10000 > 1  [#permalink]

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New post 27 Mar 2019, 07:10
If its the former. then A is sufficienf

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Re: If y is an integer, is 3^y/10000 > 1  [#permalink]

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New post 27 Mar 2019, 07:33
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AkshdeepS wrote:
If y is an integer, is 3^y/10000 > 1?

1. 100/10^y < 0.01

2.\(\sqrt{3y} = 243\)


Source : Barron's GMAT


Are you sure the OA is correct?

Here's what I did:
Given: y is an integer
To find: is \(\frac{3^y}{10000}\) > 1 Yes/No question

Statement (1): \(\frac{100}{10^y}\) < 0.01
For this statement to work, y≥5
If y=5, \(\frac{3^5}{10000}\) < 1 NO
If y=6, \(\frac{3^6}{10000}\) < 1 NO
We can get YES if y increases.
Still different answers, INSUFFICIENT!

Statement (2): \(\sqrt{3y} = 243\)
Squaring both the sides, 3y=243*243 => y= 81*243 = some big number and \(\frac{3^y}{10000}\) > 1 YES as numerator will be greater. SUFFICIENT!

Answer should be option B!

Please recheck the question and OA.
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Re: If y is an integer, is 3^y/10000 > 1  [#permalink]

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New post 27 Mar 2019, 13:07
I'll post how I did it. I hope it will help

The value is \(\frac{3^{y}}{1000} > 1\) because there's no parenthesis. Exponents are prioritary

\(<=> 3^{y} > 1000\)

(Optionnal Part) :

\(<=> y = \frac{1000}{log(3)}\) (all the log(x) for every 0 < x < 1 are inferior to 1.

\(<=> y > 1000\)

(1) :

\(\frac{100}{10^y} < 0.01\)

\(<=> 100 < 0.01 * 10^{y}\)

\(<=> \frac{100^{2}}{10^{-3}} < 10^{y}\)

\(<=> 100^{5} < 10^{y}\)

\(<=> 5 < y\)

\(<=> y > 5\)

Which is Sufficient to conclude whether of not the statement is true or false

(2)

\(\sqrt{3y} = 243\)

\(<=> y = \frac{243^{2}}{3}\)

(Optionnal Part) :

\(200^{2} = 4 00 00\)

\(<=> y > 10000\) (approximately)

Which is Sufficient to conclude whether of not the statement is true or false
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Re: If y is an integer, is 3^y/10000 > 1  [#permalink]

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New post 27 Mar 2019, 17:31
1
xhaltar wrote:
I'll post how I did it. I hope it will help

The value is \(\frac{3^{y}}{1000} > 1\) because there's no parenthesis. Exponents are prioritary

\(<=> 3^{y} > 1000\)

(Optionnal Part) :

\(<=> y = \frac{1000}{log(3)}\) (all the log(x) for every 0 < x < 1 are inferior to 1.

\(<=> y > 1000\)


You've made a small mistake with the logarithms. (You don't ever need to use logarithms on the GMAT, by the way, and I've never found a problem where they'd be particularly helpful - so it's a sign that you might be making a problem more complicated than it really is!)

However, here's how the simplification should look, if you choose to simplify it that way:

log(3^y) > log(1000)

y*log(3) > 3

y > 3/log(3) (which is approximately 6.3.)

So, y doesn't have to be greater than 1000, it only has to be greater than ~6.3 for the answer to be 'yes'.

Also, be cautious about using language like "Sufficient to conclude whether or not the statement is true or false." You're never trying to figure out whether the statement is true or false. In fact, you should assume that every statement is always true. The only thing in question is what the answer to the question is.

So, for example, the first part of this problem simplifies to:

"Is y > 6.3?

(1) y >=5 "

It's true that y>=5, but we don't know whether it's greater than or less than 6.3. Therefore, that statement is insufficient.
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Re: If y is an integer, is 3^y/10000 > 1  [#permalink]

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New post 27 Mar 2019, 23:23
AkshdeepS wrote:
If y is an integer, is 3^y/10000 > 1?

1. 100/3^y < 0.01

2.\(\sqrt{3y} = 243\)



Statement 1 edited. Inconvenience regretted. It was not 10^y but 3^y.

Thank you.

Source : Barron's GMAT


Statement 1 edited.
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Re: If y is an integer, is 3^y/10000 > 1   [#permalink] 27 Mar 2019, 23:23
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