From 1990 to 2000, there is a projected decrease in the number of

Question

https://gmatclub.com/forum/download/file.php?id=35486 
From 1990 to 2000, there is a projected decrease in the number of criminals for which of the following categories?

I. Vice
II. Assault
III. White Collar

(A) None
(B) I only
(C) II only
(D) II and III only
(E) I, II, and III

Source:   Nova GMAT  
Difficulty Level:   550

sasidharrs · Answer

I don't think any of the 3 categories are showing any decrease.
Looks like the world is getting worse ..option A

amanvermagmat · Answer

1990 
Vice = 17% of 10 million = 1.7 million
Assault = 20% of 10 million = 2 million 
White Collar = 38% of 10 million = 3.8 million

2000 
Vice = 15% of 20 million = 3 million 
Assault = 20% of 20 million = 4 million 
White Collar = 30% of 20 million = 6 million

As is clear, number of criminals in none of the three categories is decreasing. So  Option A is the answer

amanvermagmat · Answer

Another way to look at this question:

From 1990 to 2000, total criminal population is getting doubled (10 to 20 million). So for the number of a particular category to be same, its percentage in total must be half.

Eg - 10% of 10 million = 1 million and 5% of 20 million is also = 1 million. Basically, a% of x = a/2 % of 2x

So if a category is to have even  equal number of criminals in 1990 and 2000, its % share in total in 2000 must be half of its % share in total in 1990 . And  for a category to actually depict a decrease in the number of criminals, its % share in total in 2000 must be less than half of its % share in total in 1990 . (so eg - Assault is 20% of 10 million in 1990; for it to actually decrease - it must get less than 10% of the total 20 million in 2000. But its not happening, so Assault number is not decreasing)

We can see that none of the three categories' share is less than half in terms of % share from 1990 to 2000. So None, answer is  option A

From 1990 to 2000, there is a projected decrease in the number of

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From 1990 to 2000, there is a projected decrease in the number of

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