Question 1151735
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In 1900 the ratio was 4% = 0.04.


In 2010 the ratio was 13% = 0.13.


The answer to the problem's question is  {{{(0.13-0.04)/0.04}}} = {{{0.09/0.04}}} = {{{9/4}}} = 2.25 as a decimal, or 225% as percentage.


<U>ANSWER</U>.  The proportion of the US population that is 65 years or older increased by 225% from 1900 to 2010.
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