OG 12th ED DS62 Timing Question

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piyushdabomb: Master | Next Rank: 500 Posts; Posts: 115; Joined: Sun Sep 28, 2008 5:31 pm; Thanked: 4 times

by piyushdabomb » Tue Mar 16, 2010 8:23 pm

Guys,

For the DS Qn #62, try it and let me know how long its taking you to get an answer.

My first attempt took me 2:45 to answer the question and my second attempt took me 3:10 to answer the question. Is this question supposed to be a question I need to know how to do in under 2 minutes?

How do I know if I'm realistically supposed to answer a question in under 2 minutes or not without constantly posting my question (like this one) here?

-------------------
Sincerely,

Piyush A.

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Source: Beat The GMAT — Data Sufficiency | Tue Mar 16, 2010 8:23 pm

[email protected]: Senior | Next Rank: 100 Posts; Posts: 33; Joined: Tue Jan 19, 2010 11:15 pm; Location: India; Thanked: 2 times

by [email protected] » Tue Mar 16, 2010 8:27 pm

Can you post this question please ?

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papgust: Community Manager; Posts: 1537; Joined: Mon Aug 10, 2009 6:10 pmFollowed by: 252 members; Thanked: 653 times

by papgust » Tue Mar 16, 2010 8:37 pm

Moved to Data Sufficiency folder!

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piyushdabomb: Master | Next Rank: 500 Posts; Posts: 115; Joined: Sun Sep 28, 2008 5:31 pm; Thanked: 4 times

by piyushdabomb » Wed Mar 17, 2010 6:51 am

I would, but it's in the OG book. Why not try it?

The problem is that I'm at work and it'd be wrong if I just took out my book right now in front of my colleagues!

-------------------
Sincerely,

Piyush A.

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student22: Master | Next Rank: 500 Posts; Posts: 216; Joined: Mon Dec 21, 2009 10:26 am; Thanked: 16 times

by student22 » Wed Mar 17, 2010 9:23 am

Sure, I'll post it and the question should only take 30seconds tops to solve, I'll go over my solution and reasoning.

Code: Select all

For a convention, a hotel charges a daily room rate of $120 for 1 person and x dollars for each additional person. What is the charge for each additional person?

&#40;1&#41; The daily cost per person for 4 people sharing the cost of a room equally is $45.
&#40;2&#41; The daily cost per person for 2 people sharing the cost of a room equally is $25 more than the corresponding cost for 4 people.

OA: D

Let x be dollars (as stated in the question).

Statement 1:

120 + x(4 - 1) = 45 --> That's all you need, you isolated 1 variable. No need to solve any further. Suff.

Statement 2:

120 + x(2 - 1) = 120 + x(4 - 1) + 45 --> Same deal, you isolated x. No need to solve any further. Suff.

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gmatmachoman: Legendary Member; Posts: 2326; Joined: Mon Jul 28, 2008 3:54 amFollowed by: 2 members; Thanked: 173 times; GMAT Score:710

by gmatmachoman » Wed Mar 17, 2010 11:13 am

student22 wrote:Sure, I'll post it and the question should only take 30seconds tops to solve, I'll go over my solution and reasoning.
Code: Select all
For a convention, a hotel charges a daily room rate of $120 for 1 person and x dollars for each additional person. What is the charge for each additional person?

&#40;1&#41; The daily cost per person for 4 people sharing the cost of a room equally is $45.
&#40;2&#41; The daily cost per person for 2 people sharing the cost of a room equally is $25 more than the corresponding cost for 4 people.
OA: D

Let x be dollars (as stated in the question).

Statement 1:

120 + x(4 - 1) = 45 --> That's all you need, you isolated 1 variable. No need to solve any further. Suff.

Statement 2:

120 + x(2 - 1) = 120 + x(4 - 1) + 45 --> Same deal, you isolated x. No need to solve any further. Suff.

I amnot sure if i can finish in 30 secs.I took more than a minute...(but correct soln)
The step above mentioned by the other user is NOT correct.

st 1:120 + 3x =45(4) = 180.
st 2:(120 + x )/2= ((120 +3x)/4) +25

solving any of the equations u shuld get X=20$.

SO D....

After all GMAT cant ask our IIT maths...so GMAC need to be contended with tough English that really make us(atleast me) scary..Uffffffffffffffffffffff

R&D on GMAT algorithm:

https://www.beatthegmat.com/r-d-on-gmat- ... tml#305739

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student22: Master | Next Rank: 500 Posts; Posts: 216; Joined: Mon Dec 21, 2009 10:26 am; Thanked: 16 times

by student22 » Wed Mar 17, 2010 1:23 pm

Good catch, I solved it too quickly and missed the part of per person. So yes you have to multiply by 4 in the first one and divide each one by 2 and 4 respectively on the second statement.

But my original point still stands, the question gives you three variables. X for dollars for additional persons AND let's say N for the number of additional persons AND the total cost T of the room.

What you should be looking for in each statement is an answer to 2 of those questions. Statement 1 gives you an answer to the total cost 45 * 4 and the number of people N which is 4. So you intuitively know without even writing an equation that you only have one variable left, X.

The second statement gives you N by giving you 2 and 4 people. And it answers the question of total cost by telling you the relative price, that the cost for 2 people is equal to + 25 for the cost of 4 people. This tells you that you only have X left to solve. Again, no need to even write an equation.

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[email protected]: Senior | Next Rank: 100 Posts; Posts: 33; Joined: Tue Jan 19, 2010 11:15 pm; Location: India; Thanked: 2 times

by [email protected] » Wed Mar 17, 2010 7:29 pm

piyushdabomb wrote:Guys,

For the DS Qn #62, try it and let me know how long its taking you to get an answer.

My first attempt took me 2:45 to answer the question and my second attempt took me 3:10 to answer the question. Is this question supposed to be a question I need to know how to do in under 2 minutes?

How do I know if I'm realistically supposed to answer a question in under 2 minutes or not without constantly posting my question (like this one) here?

Answer : D

Took me around 30 secs to do this. May be because I have done this problem earlier.
But in any case I dont think it should take more than 1 minute to complete. This would probably be categorized as a 600-700 level problem.

GMAT GMAT Whatcha gona do.. Whatcha gona do when I come for you...

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