Answer-
The total interest after 3 years is Rs.5760 .
Solution-
Total money borrowed = Rs.12000
Out of those Rs.4000 is of 18% interest rate and remaining 12000-4000=8000 is of 15% interest rate.
[tex]\text{Total interest}=\frac{P_1\times r_1\times t}{100}+\frac{P_2\times r_2\times t}{100}[/tex]
Where,
P₁ = principal amount = Rs.4000
P₂ = principal amount = Rs.8000
r₁ = rate of interest of P₁ = 18%
r₂ = rate of interest of P₂ = 15%
t = time period = 3 years
[tex]\text{Total interest}=\frac{4000\times 18\times 3}{100}+\frac{8000\times 15\times 3}{100}=2160+3600=5760[/tex]
