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Source: Official Guide for GMAT Review 2016 Problem Solving; #160


The price of lunch for 15 people

The price of lunch for 15 people was $207.00, including a 15 percent gratuity for service. What was the average price per person, EXCLUDING the gratuity?

2 Explanations


Ricardo Martinez

Would be useful if you continued showing the process in the long division

Apr 21, 2018 • Comment

Sam Kinsman

Hi Ricardo,

The part of the long division process that wasn't fully explained was how we know that 1.15 goes into 92 exactly 80 times. So I'm guessing that this is the part you are referring to!

Well, during long division, sometimes it is helpful to "guess and check." For example, you know that since 1.15 is slightly bigger than 1, the result of 92/1.15 has to be a bit less than 92. So we could start by trying 70. We can do that multiplication by hand, to get 80.5. Ok, we know we need a bigger number - so we try 75. 75*1.15=86.25. Still too small. So try 80*1.15, and you get exactly 92 - so that's the number we need!

For more on long division, you might want to check out some of the videos here

Apr 23, 2018 • Reply


Gravatar Mike McGarry, Magoosh Tutor

Aug 17, 2015 • Comment

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