BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

og ps 123

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 789
Joined: Sun May 06, 2007 1:25 am
Location: Southern California, USA
Thanked: 15 times
Followed by:6 members

og ps 123

by resilient » Sun Feb 10, 2008 11:09 pm
I believe I am making this much harder than it really is. please let me know.

The price of lunch for 15 peoplewas $207.00including a 15% gratuity for service. What was the average price per person, Excluding gratuity?

a.11.73
b.12.00
c.13.80
d.14.00
e.15.87

qa iis B i chose A
Appetite for 700 and I scraped my plate!
Top
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 63
Joined: Sun May 20, 2007 10:29 am
Thanked: 3 times

Re: og ps 123

by mleviko » Mon Feb 11, 2008 2:57 am
Enginpasa1 wrote:I believe I am making this much harder than it really is. please let me know.

The price of lunch for 15 peoplewas $207.00including a 15% gratuity for service. What was the average price per person, Excluding gratuity?

a.11.73
b.12.00
c.13.80
d.14.00
e.15.87

qa iis B i chose A
I would simply plug-in the results and see what fits. The most attractive option to start with is B , because 12 is an easy to number to do calc with.

If the average price per person is 12, then 15 people paid 15 X 12 = 180 for their lunch, without gratuity. gratuity is 15%, or 180 X 15 / 100 = 27. 180 + 27 = 207 which was the total price they paid, so answer B.
Smashed the GMAT: 760
Top
Senior | Next Rank: 100 Posts
Posts: 49
Joined: Sun Jul 01, 2007 5:56 pm
Thanked: 3 times

by smushkas » Mon Feb 11, 2008 3:39 am
Hey there,
If you got [A], then must be doing it this way [0.85*207] / 15 = 11.73. But, it should be done in a slightly different way
==> [207 / 1.15] / 15 = 180 / 15 = 12

Hope this helps!
Top
Legendary Member
Posts: 789
Joined: Sun May 06, 2007 1:25 am
Location: Southern California, USA
Thanked: 15 times
Followed by:6 members

ok

by resilient » Mon Feb 11, 2008 10:47 am
i often forget to combine the two percents in that manner.. I also keep forgetting of a great tool of backsolving. thanks folks[spoiler][/spoiler]
Appetite for 700 and I scraped my plate!
Top
Newbie | Next Rank: 10 Posts
Posts: 1
Joined: Tue Dec 07, 2010 3:53 am

by vaghul » Mon Dec 20, 2010 4:00 pm
Common mistake is calculating tip as 15% of total bill (207 in this case)...

It should be, Original amount (x) + 15% of x = 207.
Top
Master | Next Rank: 500 Posts
Posts: 112
Joined: Wed Jan 20, 2010 5:46 am
Thanked: 1 times

by Thouraya » Tue Mar 01, 2011 6:27 am
thanks for pointing this out Vaghul.. but I didn't understand why it's wrong if I assume that the total amount is 207 and then: 207- 15/100 (207) I would come up with original amount?
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 116
Joined: Wed Mar 14, 2012 1:02 pm
Thanked: 20 times
Followed by:11 members
GMAT Score:760

by mcdesty » Mon Jul 02, 2012 11:24 am
X(Lunch Price) + 15%X = 207
X( 1 + 3/20) = 207
23X/20=207
X= 180
Average = 180(Lunch price)/15(Number of people)
Average = 12

The key here is realizing that 15% is 3/20...and that 207/23 is 9..(This question shouldn't take you more the 40 secs if you recognize these two steps)

I don't like the testing numbers strategy because if you aren't lucky, you will waste time.

IF YOU HAVE TO MULTIPLY OR DIVIDE A PERCENT/DECIMAL, CONSIDER FRACTIONS!!
Top
Senior | Next Rank: 100 Posts
Posts: 56
Joined: Mon Sep 17, 2012 12:27 pm
Thanked: 13 times
Followed by:1 members
GMAT Score:710

by buzzdeepak » Wed Feb 06, 2013 4:57 pm
yea, good point...you can get stuck in endless calculations which might take forever in GMAT to calculate 207/1.15.

I realized this and then used second method - substituting the answers and luckily 12 (first easy number) worked out perfectly.

But, I agree, fractions work better / quicker in this case.
Top
Post new topic Post Reply
• Page 1 of 1