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The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is

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The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is [#permalink]

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09 May 2011, 05:51
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The value of $$\frac{2^{(-14)} + 2^{(-15)} + 2^{(-16)} + 2^{(-17)}}{5}$$ is how many times the value of $$2^{(-17)}$$?

A. 3/2
B. 5/2
C. 3
D. 4
E. 5
[Reveal] Spoiler: OA
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09 May 2011, 06:31
2^-14+2^-15+2^-16+2^-17/5

= 2^-17(2*3 + 2^2 + 2 + 1)/5

= = 2^-17 * 15/5 = 3(2^-17)

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09 May 2011, 06:44
2^(-14)/5 [ 1+ 2^(-1) + 2^(-2) + 2^(-3)]

2^(-14)/5 [ 3/2 + 3/2 * 1/4]

2^(-14)/5[3/2 * 5/4]

2^(-17)*3

Hence C.
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The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is [#permalink]

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14 Apr 2012, 12:56
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The value of $$\frac{2^{(-14)} + 2^{(-15)} + 2^{(-16)} + 2^{(-17)}}{5}$$ is how many times the value of $$2^{(-17)}$$?

A. 3/2
B. 5/2
C. 3
D. 4
E. 5

Last edited by Bunuel on 19 Jul 2016, 20:58, edited 2 times in total.
Edited the question
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Re: The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is [#permalink]

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14 Apr 2012, 13:50
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andih wrote:
The value of (2^-14)+(2^-15)+(2^-16) + (2^-17) is how times the value of 2^-17?

A. 3/2

B. 5/2

C. 3

D. 4

E. 5

The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is how many times the value of 2^(-17)?

We need to find the value of: $$\frac{\frac{1}{5}*(2^{-14}+2^{-15}+2^{-16}+2^{-17})}{ 2^{-17}}=\frac{\frac{1}{5}*(\frac{1}{2^{14}}+\frac{1}{2^{15}}+\frac{1}{2^{16}}+\frac{1}{2^{17}})}{\frac{1}{2^{17}}}$$.

Now, $$\frac{\frac{1}{5}*(\frac{1}{2^{14}}+\frac{1}{2^{15}}+\frac{1}{2^{16}}+\frac{1}{2^{17}})}{\frac{1}{2^{17}}}=\frac{2^{17}}{5}*(\frac{1}{2^{14}}+\frac{1}{2^{15}}+\frac{1}{2^{16}}+\frac{1}{2^{17}})=\frac{1}{5}*(2^3+2^2+2+1)=\frac{1}{5}*15=3$$.

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Re: The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is [#permalink]

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15 Apr 2012, 06:47
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if you take 2^(-17) common in the numerator, you will have 2^(-17) { 8 + 4 + 2 + 1} which equals 15.
This 15 cancels with 5 in the denominator and leaves {3} 2^-(17). Slightly quicker this way i feel.
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02 Jul 2013, 00:17
Bumping for review and further discussion*. Get a kudos point for an alternative solution!

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Re: The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is [#permalink]

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09 Oct 2013, 19:41
Bunuel wrote:
andih wrote:
The value of (2^-14)+(2^-15)+(2^-16) + (2^-17) is how times the value of 2^-17?

A. 3/2

B. 5/2

C. 3

D. 4

E. 5

The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is how many times the value of 2^(-17)?

We need to find the value of: $$\frac{\frac{1}{5}*(2^{-14}+2^{-15}+2^{-16}+2^{-17})}{ 2^{-17}}=\frac{\frac{1}{5}*(\frac{1}{2^{14}}+\frac{1}{2^{15}}+\frac{1}{2^{16}}+\frac{1}{2^{17}})}{\frac{1}{2^{17}}}$$.

Now, $$\frac{\frac{1}{5}*(\frac{1}{2^{14}}+\frac{1}{2^{15}}+\frac{1}{2^{16}}+\frac{1}{2^{17}})}{\frac{1}{2^{17}}}=\frac{2^{17}}{5}*(\frac{1}{2^{14}}+\frac{1}{2^{15}}+\frac{1}{2^{16}}+\frac{1}{2^{17}})=\frac{1}{5}*(2^3+2^2+2+1)=\frac{1}{5}*15=3$$.

Why do we divide by 2^-17?

Thanks,
C
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Re: The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is [#permalink]

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09 Oct 2013, 20:15
runningguy wrote:
Bunuel wrote:
andih wrote:
The value of (2^-14)+(2^-15)+(2^-16) + (2^-17) is how times the value of 2^-17?

A. 3/2

B. 5/2

C. 3

D. 4

E. 5

The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is how many times the value of 2^(-17)?

We need to find the value of: $$\frac{\frac{1}{5}*(2^{-14}+2^{-15}+2^{-16}+2^{-17})}{ 2^{-17}}=\frac{\frac{1}{5}*(\frac{1}{2^{14}}+\frac{1}{2^{15}}+\frac{1}{2^{16}}+\frac{1}{2^{17}})}{\frac{1}{2^{17}}}$$.

Now, $$\frac{\frac{1}{5}*(\frac{1}{2^{14}}+\frac{1}{2^{15}}+\frac{1}{2^{16}}+\frac{1}{2^{17}})}{\frac{1}{2^{17}}}=\frac{2^{17}}{5}*(\frac{1}{2^{14}}+\frac{1}{2^{15}}+\frac{1}{2^{16}}+\frac{1}{2^{17}})=\frac{1}{5}*(2^3+2^2+2+1)=\frac{1}{5}*15=3$$.

Why do we divide by 2^-17?

Thanks,
C

It is given in the question.

We need to find "how many times the value of 2^(-17)" which means the entire expression is divided by 2^(-17). The quotient is the answer

Hope it is clear
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Re: The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is [#permalink]

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21 Oct 2013, 08:50
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andih wrote:
The value of $$2^{-14} + 2^{-15} + 2^{-16} + 2^{-17}/5$$ is how many times the value of 2^{-17}?

A. 3/2
B. 5/2
C. 3
D. 4
E. 5

$$2^{-14} + 2^{-15} + 2^{-16} + 2^{-17}/5$$ -----> Factor out from the nominator $$2^{-17}$$
$$2^{-17}(2^3+2^2+2^1+1)/5$$
$$2^{-17}(8+4+2+1)/5$$
$$2^{-17}*15/5$$
$$2^{-17}*3$$

Therefore, the equation is $$3$$ times the value of $$2^{-17}$$ and our answer is
[Reveal] Spoiler:
C

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Re: The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is [#permalink]

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26 Feb 2014, 01:56
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suk1234 wrote:
andih wrote:
The value of $$2^{-14} + 2^{-15} + 2^{-16} + 2^{-17}/5$$ is how many times the value of 2^{-17}?

A. 3/2
B. 5/2
C. 3
D. 4
E. 5

$$2^{-14} + 2^{-15} + 2^{-16} + 2^{-17}/5$$ -----> Factor out from the nominator $$2^{-17}$$
$$2^{-17}(2^3+2^2+2^1+1)/5$$
$$2^{-17}(8+4+2+1)/5$$
$$2^{-17}*15/5$$
$$2^{-17}*3$$

Therefore, the equation is $$3$$ times the value of $$2^{-17}$$ and our answer is
[Reveal] Spoiler:
C

How many times the value of 2^{-17} means just multiply the complete equation by 2^17 (Please note the power sign has been changed) & we get the answer

(8+4+2+1) / 5 = 3 = Answer = C
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30 Jun 2014, 17:31
the value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is how many times the value of 2^(-17)?

Lets say (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 = x* 2^(-17) --> (X times of 2^(-17)), So basically we need to find what is x ?

looks like we need to simplify the exponents to make given values in form desire one ..

lets Simplify Given Part , if we take 2^(-17) from numerator the simplified numerator will be ..

2^(-17)(2^(3) + 2^(2) + 2^(1) + 2^(0) )/5 = x*2^(-17)

why 2^(3) + 2^(2) ..... ? because if we want to make 2^(-17) = 2^(-14) we required to add 2^(3) positive power . same for other...

now divide 2^(-17) both side , x = (2^(3) + 2^(2) + 2^(1) + 2^(0) )/5 => x= (8+4+2+1)/5 => x =15/5 => x=3 Answer is C.
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12 Sep 2014, 00:53
hi according to answer 2^17 (Please note the power sign has been changed) & we get the answer

(8+4+2+1) / 5 = 3

how you reach this (8+4+2+1)????
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16 May 2016, 22:25
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06 Jun 2016, 07:45
(2^-14 + 2^-15 + 2^-16 + 2^-17)/5 = 2^-17*(2^3 + 2^2 + 2 + 1) / 5
= 2^-17 * (15)/5 = 2^-17 * 3

Correct Option: C
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19 Jul 2016, 12:13
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21 Jul 2016, 09:41
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carollu wrote:
The value of $$\frac{2^{(-14)} + 2^{(-15)} + 2^{(-16)} + 2^{(-17)}}{5}$$ is how many times the value of $$2^{(-17)}$$?

A. 3/2
B. 5/2
C. 3
D. 4
E. 5

We start by translating the question. We are asked (2^-14) + (2^-15) + (2^-16) + (2^-17) is how times the value of 2^-17. We can express it as the following:

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22 Aug 2016, 14:15
I think we can solve it another way.
please expert correct me if I am wrong.
2^(-17)* (2^3+2^2+2^1+1)/5 = 2^(-17)*(8+4+2+1)/5
2^(-17)*(15)/5 = 2^(-17)*(3)
So finally, (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is 3 time 2^(-17).
I think It is simple and direct. but one should get the idea. It is wordy and looks complicated and let me be scared.
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Re: The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is [#permalink]

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22 Aug 2016, 14:22
Riffing on Scott's solution above. Instead of 'pulling out' a 2^-17, you can multiply both sides by 2^17 to simplify all of the exponents.
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Re: The value of (2^(-14) + 2^(-15) + 2^(-16) + 2^(-17))/5 is   [#permalink] 22 Aug 2016, 14:22

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