Question

1.An investor Nx in bank M at the rate of 6%simple interest per annum and Ny in bank N at the rate of 8% simple interest per annum. If a total of #8,000,000.00 as interest from two banks after 4 years , calculate the (i) values of X and y; (ii) interest paid by the second bank

Answer 1

Total amount invested 

$$x+y=8,000,000.00$$

Interest from bank $M = x×\dfrac{6}{100}×4=0.24x$

Interest from bank $N = y×\dfrac{8}{100}×4=0.32y$

The investor received a total of $A$ as interest from the two banks after 4 years

$$0.24x+0.32y=A$$

$$x+y=8000000$$ $$0.24x+0.32y=A$$

$$x=8000000-y$$ $$0.24(8000000-y)+0.32y=A$$

$$x=8000000-y$$ $$0.08y=A-1920000$$

$$x=8000000-y$$ $$y=12.5A-24000000$$

$$x=32000000-12.5A$$ $$y=12.5A-24000000$$

(i)

$$x=32000000-12.5A$$ $$y=12.5A-24000000$$

(ii)

$$0.32(12.5A-24000000)=4A-7680000$$

Interest paid by the second bank is $N(4A-7680000).$

If $A=2,320,000.00,$ then

$$x=3,000,000.00$$ $$y=5,000,000.00$$

Interest paid by the second bank is $N1,600,000.00.$