On decreasing the price of a colour TV by 20%, its sale is increased by 30%. The effect on the revenue is?  Select:  A) 4% decrease  B) 4% increase  C) 16% decrease  D) 16% increase  E) none of these
Net% change in revenue   = ( x + y + xy/100) %   = [-20 + 30 + ( -20 x 30)/100]% or 4%   ANSWER:4% increase
<result>B</result>
On decreasing the price of a colour TV by 20%, its sale is increased by 30%. The effect on the revenue is?