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When frightened, a certain puffer fish rapidly expands by 70%. Shortly

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When frightened, a certain puffer fish rapidly expands by 70%. Shortly  [#permalink]

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New post 13 Feb 2017, 03:11
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Question Stats:

51% (01:13) correct 49% (01:00) wrong based on 108 sessions

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When frightened, a certain puffer fish rapidly expands by 70%. Shortly thereafter, the fish contracts by 70%. By what approximate percentage does the puffer fish then need to expand again in order to return to its initial size?

A. 0%
B. 20%
C. 50%
D. 70%
E. 100%

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When frightened, a certain puffer fish rapidly expands by 70%. Shortly  [#permalink]

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New post Updated on: 13 Feb 2017, 21:11
3
Bunuel wrote:
When frightened, a certain puffer fish rapidly expands by 70%. Shortly thereafter, the fish contracts by 70%. By what approximate percentage does the puffer fish then need to expand again in order to return to its initial size?

A. 0%
B. 20%
C. 50%
D. 70%
E. 100%


let x be the original size
x expands by 70% => 1.7*x then contracts by 70% => 1.7*0.3*x = 0.51*x
To expand again in order to return to its initial size the puffer needs almost 50% to get back to original size x
So it needs to expand by 100%.

Hence Option E is correct.
Hit Kudos if you liked it 8-).

Originally posted by 0akshay0 on 13 Feb 2017, 04:00.
Last edited by 0akshay0 on 13 Feb 2017, 21:11, edited 1 time in total.
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Re: When frightened, a certain puffer fish rapidly expands by 70%. Shortly  [#permalink]

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New post 13 Feb 2017, 07:05
2
Bunuel wrote:
When frightened, a certain puffer fish rapidly expands by 70%. Shortly thereafter, the fish contracts by 70%. By what approximate percentage does the puffer fish then need to expand again in order to return to its initial size?

A. 0%
B. 20%
C. 50%
D. 70%
E. 100%


Assuming the initial size of a puffer to be 100.

After expansion by 70%, new size is 170.

After contraction by 70%, the new size is 51. (30% of 170)

Now the puffer has to almost double itself to gain its original size of 100. So the size has to increase by 100%.

Answer E

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When frightened, a certain puffer fish rapidly expands by 70%. Shortly  [#permalink]

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New post 17 Feb 2017, 04:36
Answer : [E]

Net change = +70 -70 (+)(-) (70*70) / (100* 100) = 49%

Resultant size = 51%

Required growth percent = 49 / 51 =100 %
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Re: When frightened, a certain puffer fish rapidly expands by 70%. Shortly  [#permalink]

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New post 23 Feb 2017, 10:29
1
Bunuel wrote:
When frightened, a certain puffer fish rapidly expands by 70%. Shortly thereafter, the fish contracts by 70%. By what approximate percentage does the puffer fish then need to expand again in order to return to its initial size?

A. 0%
B. 20%
C. 50%
D. 70%
E. 100%


We can let x = the initial size of the fish. Since it expands by 70% and then contracts by 70%, we can create the following expression:

x(1.7)(0.3) = x(0.51)

To return to its original size, the fish needs to increase by roughly 100%, since 2(0.51x) = 1.02x.

Answer: E
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When frightened, a certain puffer fish rapidly expands by 70%. Shortly  [#permalink]

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New post 08 Aug 2018, 22:51
Let 100 be the original size of the fish.

It expands by 70%=170/100, it contracts back by 70%=30/100=>(170/100)(30/100)=51, we get 51~50
So now it is on 50 and has to go back to 100=> (100-50)*100/50=100%

Answer (E)
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Re: When frightened, a certain puffer fish rapidly expands by 70%. Shortly  [#permalink]

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New post 09 Aug 2018, 09:25
1
Bunuel wrote:
When frightened, a certain puffer fish rapidly expands by 70%. Shortly thereafter, the fish contracts by 70%. By what approximate percentage does the puffer fish then need to expand again in order to return to its initial size?

A. 0%
B. 20%
C. 50%
D. 70%
E. 100%

+70 - 70 +(70)(-70)/100

= 0 - 49

Thus, The fish have to regain approx 50% of its initial size, Answer must be (C)
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Re: When frightened, a certain puffer fish rapidly expands by 70%. Shortly &nbs [#permalink] 09 Aug 2018, 09:25
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