If it were discovered that the value of imports shown for 2007 was incorrect and should have been $5 billion instead, then the average (arithmetic mean)value of imports per year for the 10 years shown would have been approximately how much less?

A $200 million
B $50 million
C $20 million
D $7 million
E $5 million




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Sandy
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Given: The graph shows $7 billion for 2007, when it should actually be $5 billion.

One way to solve this question is to estimate the imports for all 10 years (with $7 billion for 2007), and then find the average.
Then estimate the imports for all 10 years (with $5 billion for 2007), and then find the average
Then find the difference between those averages.
This is more work than we need to do.

Since 9 of the values don't change, we can let x = the sum of those 9 values.

Now we'll find two averages:

Average value when we use $7 billion for 2007 = (x + 7)/10
Average value when we use $5 billion for 2007 = (x + 5)/10

So, the DIFFERENCE = (x + 7)/10 - (x + 5)/10
= (x/10 + 7/10) - (x/10 + 5/10)
= 2/10 (billion dollars)
= 200 million dollars

Answer: A

Cheers,
Brent
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Brent Hanneson – Creator of greenlighttestprep.com
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