A single refined oil can contains 20% impurities. After double – refining it contains 4% impurities. How much of double- refined oil can be obtained from 30 litres of single refined oil? Choices
A) 24.0 litres B) 24.8 litres C) 25.0 litres D) 25.5 litres E) 35.0 litres
Exp. On double- refining impurity decreases from 20% to 4%., but the   amount of pure oil in both cases remains constant,   i.e, 96% of double refined oil = 80% of single refined oil.   Let x be the quantity of double-refined oil   Then 96*x/100 = 80*30/100, x = 30*80 /96= 
<gadget id="calculator">30*80 /96</gadget>
<output>25</output>
25   Answer:25.0 litres
<result>C</result>
A single refined oil can contains 20% impurities. After double – refining it contains 4% impurities. How much of double- refined oil can be obtained from 30 litres of single refined oil?