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# 13th Edition DS questions #41 and #60

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Intern
Joined: 14 Sep 2016
Posts: 1
13th Edition DS questions #41 and #60  [#permalink]

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17 Apr 2018, 09:45
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Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 2 sessions

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I want to start out by saying these are pretty easy questions but I don't understand one concept. Mathematically both questions make sense but I don't understand why they are beings solved the way they are.

#41

Is 4^x+y =8^10. I simplified the given equation. 2^2(x+y)=2^3*10-->2^(x+y)=2^15-->Thus x+y=15
Notes: In OG solution, you can not plug -y=9-x or y=x+9 back into the the calculated equation of x+y=15. You can manipulate (1) and (2) to get the answer. This makes sense.

Key note: You can't plug in equation (1) into original equation.

(1) x-y=9
(2) x/y=1/4

#60
What is the value of n in the equation -25+19+n=s> -->simplify to n=s+6. Plug in S--> sufficient and plug in S4 sufficient.

Key note: Why can you plug equation 2 into the original equation n=s+6? Why is #41 different than #60.

(1) s=2
(2) n/s=4
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Joined: 26 Feb 2016
Posts: 3335
Location: India
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Re: 13th Edition DS questions #41 and #60  [#permalink]

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17 Apr 2018, 12:43
Hi emoroz

These questions have been discussed here

#41. https://gmatclub.com/forum/is-4-x-y-139120.html
#60. https://gmatclub.com/forum/what-is-the- ... 40251.html
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You've got what it takes, but it will take everything you've got
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Joined: 02 Sep 2009
Posts: 58434
Re: 13th Edition DS questions #41 and #60  [#permalink]

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17 Apr 2018, 13:54
emoroz wrote:
I want to start out by saying these are pretty easy questions but I don't understand one concept. Mathematically both questions make sense but I don't understand why they are beings solved the way they are.

#41

Is 4^x+y =8^10. I simplified the given equation. 2^2(x+y)=2^3*10-->2^(x+y)=2^15-->Thus x+y=15
Notes: In OG solution, you can not plug -y=9-x or y=x+9 back into the the calculated equation of x+y=15. You can manipulate (1) and (2) to get the answer. This makes sense.

Key note: You can't plug in equation (1) into original equation.

(1) x-y=9
(2) x/y=1/4

#60
What is the value of n in the equation -25+19+n=s> -->simplify to n=s+6. Plug in S--> sufficient and plug in S4 sufficient.

Key note: Why can you plug equation 2 into the original equation n=s+6? Why is #41 different than #60.

(1) s=2
(2) n/s=4

All OG questions: https://gmatclub.com/forum/gmac-officia ... 40610.html
_________________
Re: 13th Edition DS questions #41 and #60   [#permalink] 17 Apr 2018, 13:54
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