<PRE><B>Question 329189</B>
Let {{{x}}} = ml of heavy cream that needs to b added
given:
Butterfat in heavy cream = {{{.4x}}} ml
Amount of 20% light cream = {{{1000}}} ml
Butterfat in {{{1000}}} ml of light cream= {{{.2*1000 = 200}}} ml
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In words:
(total ml of butterfat I end up with)/(total ml of mixture) = .36
{{{(.4x + 200)/(x + 1000) = .36}}}
{{{.4x + 200 = .36*(x + 1000)}}}
{{{.4x + 200 = .36x + 360}}}
{{{.04x = 360 - 200}}}
{{{.04x = 160}}}
{{{x = 4000}}}
4000 ml or 4 liters of heavy cream must be added
check answer:
{{{(.4x + 200)/(x + 1000) = .36}}}
{{{(.4*4000 + 200)/(4000 + 1000) = .36}}}
{{{1600 + 200 = .36*5000}}}
{{{1800 = 1800}}}
OK  
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