Question 4

# In how many years will Rs. 2 lakh double itself at 11.5% per annum simple interest?

Solution

Let say after a Time period (T) 'x'  years the amount Rs. 2 lakh gets doubled at a rate of interest (R) = 11.5% per annum

Initial principle amount (P) = 2,00,000 Rs.

Simple Interest (I)  for 'x' years is given by I = $$PTR\div 100$$ = $$200000\times x\times 11.5\div 100$$

=> I = $$23000\times x$$.

Final Principle amount (P') = P + I = $$2\times P$$ (as given)

=> I = $$2\times P - P$$ = P

=> $$23000\times x$$ = 200000

=> x = $$200000\div 23000$$

=> x = 8.695 = between 8 and 9.