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# If 3^k is a divisor of the product of all even integers between 2

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Senior Manager
Joined: 20 Aug 2015
Posts: 392
Location: India
GMAT 1: 760 Q50 V44
If 3^k is a divisor of the product of all even integers between 2 [#permalink]

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07 Feb 2016, 18:08
5
4
00:00

Difficulty:

45% (medium)

Question Stats:

60% (01:19) correct 40% (01:02) wrong based on 126 sessions

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If $$3^k$$ is a divisor of the product of all even integers between 2 and 30 (inclusive), what is the maximum value of k?

A. 4
B. 6
C. 10
D. 13
E. 14
Math Expert
Joined: 02 Aug 2009
Posts: 5936
Re: If 3^k is a divisor of the product of all even integers between 2 [#permalink]

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07 Feb 2016, 18:32
3
1
TeamGMATIFY wrote:
If $$3^k$$ is a divisor of the product of all even integers between 2 and 30 (inclusive), what is the maximum value of k?

A. 4
B. 6
C. 10
D. 13
E. 14

Hi,
since the Q tells us $$3^k$$ is a divisor of the product of all even integers between 2 and 30 (inclusive)
the Q basically asks us power of 3 in the product..

lets see the even multiples of 3 from 2 to 30..
6*12*18*24*30..
3^5(2*4*6*8*10)..
or 3^6*2*4*2*8*10..
ans 6
B
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Re: If 3^k is a divisor of the product of all even integers between 2 [#permalink]

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17 Feb 2016, 16:39
3
3
The way i went about it was as follows

Product of even integers between 2 and 30 are listed below:-
=2*4*6*8.........28*30 -this can also be written as 2*1 * 2*2 * 2*3.....2*14 *2*15
2^15 *(1*2*3*4.....14*15) => 2^15* 15!

3^k would not be a divisor of 2^15, so we should find out how many times 3^k would go into 15!

15/ 3 + 15/3^2 ---> 5 +1 = 6
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Joined: 30 Aug 2015
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Re: If 3^k is a divisor of the product of all even integers between 2 [#permalink]

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17 Feb 2016, 16:42
4
we can simplify it

Product of even integers between 2 and 30 are listed below:-
=2*4*6*8.........28*30 -this can also be written as 2*1 * 2*2 * 2*3.....2*14 *2*15
2^15 *(1*2*3*4.....14*15) => 2^15* 15!

3^k would not be a divisor of 2^15, so we should find out how many times 3^k would go into 15!

15/ 3 + 15/3^2 ---> 5 +1 = 6
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Re: If 3^k is a divisor of the product of all even integers between 2 [#permalink]

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23 Mar 2017, 08:25
2
TeamGMATIFY wrote:
If $$3^k$$ is a divisor of the product of all even integers between 2 and 30 (inclusive), what is the maximum value of k?

A. 4
B. 6
C. 10
D. 13
E. 14

Set of all even integers between 2 and 30 (inclusive) = { 2 , 4 , 6 , 8 , 10 , 12 , 14 , 16 , 18 , 20 , 22 , 24 , 26 , 28 , 30 }

Or, Set of all even integers between 2 and 30 (inclusive) = 2 ( 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 )

Or, Set of all even integers between 2 and 30 (inclusive) = 2*15!

Now, check the highest power of $$3^k$$ in 2*15!

Highest power of $$3^k$$ in 2*15! is = $$\frac{15}{3} => 5$$

Or, $$\frac{5}{3} = 1$$

So, the maximum value of k in $$3^k$$ is 6 ( ie, 5 + 1 )

Thus, answer must be (B) 6
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Thanks and Regards

Abhishek....

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Re: If 3^k is a divisor of the product of all even integers between 2   [#permalink] 23 Mar 2017, 08:25
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