An amount is invested in a bank at compound rate of interest, after first and third year is Rs. 1200 and Rs. 1587 respectively. What is the rate of interest?

• 15%
  If Amount=x, Compound Interest after 1 year=x[1+(r/100)]=1200 ---(i)
  Compound Interest after 3 year=x[1+(r/100)]^3=1587 ---(ii)
  Substituting value of x[1+(r/100)]=1200 from (i) into (ii)
  1200[1+(r/100)]^2=1587 or 1200[1+(2r/100)+(r^2/10000)]=1587
  r^2+200r-3225=0, (r+215)(r-15)=0, r=15
• 11 years agoHelpfull: Yes(0) No(0)