Question 767982
For now, say there are {{{ n }}} car owners in China in 2010
Also, for now, say the number doubles every {{{ t }}} years
Let {{{ C }}} = current number of car owners
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After {{{ t }}} years, there are:
{{{ C = n*2^1 }}}
After {{{ 2t }}} years, there are
{{{ C = n*2^2 }}}
After {{{ 3t }}} years, there are
{{{ C = n*2^3 }}}
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So, the general formula would be
{{{ C = n*2^k }}} where k*t is the years
since 2010 
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From 2010 to 2020 is {{{ 10 }}} years, so
{{{ k*t = 10 }}}
{{{ t = 6.3 }}}
{{{ k*6.3 = 10 }}}
{{{ k = 1.5873015 }}}
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In 2020, there will be:
{{{ C = 1.38*10^8*2^1.5873 }}}
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I can't find my calculator, but you need to convert
{{{ 2^1.5873 }}} to a number that looks like a.aaa x 10^n
Then multiply by {{{ 1.38*10^8 }}}
Then get it back to looking like a.aaa x 10^n