The price of lunch for 15 people

Sam Kinsman

That’s because 85% of 207 is not the same as the original price plus 15%! Let’s look at a more basic example:

Let’s say the price of a meal is $100 including a 50% gratuity. Using your method, we could do: $100 – (50% of 100) = $50. However, $50 is not the original price of the meal! The original price would be:

x * 1.5 = $100
x = $100 / 1.5
x = $66.67

So to solve this problem, we need to set it up such that the original price * 1.15 = $207. We can then work backwards to find the original price.

This concept is further explained here: http://magoosh.com/gmat/2012/understanding-percents-on-the-gmat/

Dec 14, 2015 • Reply

That's a smart approach too! :D

Jul 22, 2014 • Reply