ZadiaH581
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Sink-Lead Deposits CAT 3, Problem 2

by ZadiaH581 Fri Apr 15, 2016 11:35 am

Hi,

I tried attaching a picture, but for some reason I am unable to do so. On this problem the median of the zinc deposits is the average of 3.88 and 4.06. This problem explained that we actually do not have to calculate the problem and that we know that anything below 3.88 is considered below the average and anything above 4.06 is above the average. The question was a true/false question and stated below:

"Exactly half of the countries with a lead grade percentage of 2% or greater have zinc grade percentages below the median zinc grade level."

The six countries that have lead grade percentages of 2% or greater are:
Zinc Percentage Lead Percentage
Germany 3.55 2.00
United States 3.88 2.38
Canada 5.54 2.44
Mexico 4.09 2.53
Russia 3.86 3.01
Australia 6.97 4.39

The answer says it's true and explained that the United States, Germany, and Russia all have zinc grade percentages below the median zinc grade level. Now to my question, if the median is 3.88, and anything below it is considered BELOW average, then the United States with a zinc percentage of exactly 3.88 is exactly at the median and therefore not below it. This would make the question false (as then only two countries which is not half of six have zinc deposits below the median). The question also does not explicitly state less than or equal to median zinc grade levels, which would then make the answer true. I look forward to any answers!

Thank you in advance!
tim
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Re: Sink-Lead Deposits CAT 3, Problem 2

by tim Sat Apr 23, 2016 8:59 pm

There are 12 countries, so the median is halfway between the 6th and 7th ones. The median is NOT 3.88. 3.88 is BELOW the median.
Tim Sanders
Manhattan GMAT Instructor

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