A certain quantity of petrol is found to be adulterated to the extent of 10%. What proportion of the adulterated petrol should be replaced with pure petrol to take the purity level to 98%?

(a) 80% (b) 32% (c) 66.67% (d) cannot be determined.

• we have to get 98% purity.
  let x ltr pure petrol is added and the volume becomes 100ltr.
  so;
  petrol solution
  x+9/100(100-x)=98 (98 is the purity level in the final solution)
  =>x+90-0.9x=98
  =>x=80
  so 80 ltr of pure petrol is added to the adulterated solution.
• 11 years agoHelpfull: Yes(36) No(19)
• let us assume entire quantity of petrol is 100 now 10% is adulterated .remaining pure quantity is 90 and adulterated portion is 10..to take the purity level to 98% we should add 8 more.but percentage should be taken of the adulterated portion ie 8*100/10=80 %
• 9 years agoHelpfull: Yes(17) No(2)
• Ans is 80%
• 11 years agoHelpfull: Yes(7) No(24)
• can some one give a solution for this?
• 11 years agoHelpfull: Yes(3) No(15)
• ans is 80 percentage
• 11 years agoHelpfull: Yes(3) No(9)
• we have to get purity level as 98% so let us consider only purity in both RHS and LHS
  let X be the amount which is replaced. so, X is 100% pure which is only petrol. As it is replaced that means, we have (100-X) litres which are 90% pure. so the equation becomes
  X+(100-X)0.9=0.98
  x=80
  now this is proportion of previous 100 litres
  so 80/100*100= 80%
  
• 7 years agoHelpfull: Yes(2) No(2)