<PRE><B>Question 1189949</B>
&lt;br&gt;
20% of 20 gallons is 4 gallons.  So you start with 4 gallons in the jug.&lt;br&gt;
The amount added every third day is half the amount in the jug at the beginning of that day; that means the amount in the jug is multiplied by 1.5.  So&lt;br&gt;
{{{4(1.5)^x=20}}}
{{{1.5^x=5}}}&lt;br&gt;
Use logarithms, or a graphing calculator....&lt;br&gt;
Or...&lt;br&gt;
{{{1.5 = 3/2}}}
{{{1.5^x=(3/2)^x}}}&lt;br&gt;
{{{(3/2)^4 = 81/16 = 5.0625}}}&lt;br&gt;
That is slightly more than what we need; so adding more water to the jug 4 times will fill the jug.&lt;br&gt;
And since water is added to the jug every third day, the number of days it takes to fill the jug is 4*3=12.&lt;br&gt;
ANSWER: C)12&lt;br&gt;

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