When the cost of petroleum increases by 40%, a man reduces his annual consumption by
20%. The increase in his annual expenditure on petroleum is
(a) 20% (b) 12%
(c) 16% (d) 40%

• (b) 12%
  
  If existing cost=x & consumption=y, then total expenditure=xy and
  after increase, new cost=x*140/100=1.4x and consumption=y*80/100=0.8y,
  so total new expenditure=1.4x*0.8y=1.12xy
  Increase in % expendiyure=(1.12xy-xy)*100/xy=12
• 8 years agoHelpfull: Yes(5) No(0)
• a+b+ab/100;
  40-20+40*-20/100;
  12
  
• 8 years agoHelpfull: Yes(4) No(1)
• let existing cost is 10/lit
  and total consumption is 50 lit
  total cost=500
  a/c question
  10 increse by 14, and 50 decreases by 40
  total annual cost =560
  total differnce=60
  % increase in cost is (60*100)500=12% ans
• 8 years agoHelpfull: Yes(2) No(2)