The balance of a trader weighs 20% less than it should. Still the trader marks up his goods to get an overall profit of 30%. What is the mark up on the cost price?  Choose the correct choice from the following options: A) 4% B) 8% C) 25% D) 16.66% E) 9%
The most natural way to deal with 'weights' questions is by assuming values.   Say the trader's balance shows 100 gms. It is actually 80 gms because it weighs 20% less. Say, the cost price is $80 ($1/gm). Since he gets a profit of 30%, the selling price must be 80+(30/100)*80= 
<gadget id="calculator">80+(30/100)*80</gadget>
<output>104</output>
$104   Since the cost price is actually supposed to be $100 (for 100 gms) and the selling price is $104, the mark up is simply 4%.   4%ns : 4%
<result>A</result>
The balance of a trader weighs 20% less than it should. Still the trader marks up his goods to get an overall profit of 30%. What is the mark up on the cost price?