an amount of Rs 5000 is put into three/investments at the rate of interest of 6%, 7%, 8% per annum respectively; the total annual income is Rs 35800. If the combined income from first two investments is Rs 70 more than the income from the third. Find amount of each installment by matrix method.

Answer 1

If the amounts are x,y,z then

x+y+z = 5000
.06x + .07y + .08z = 3580
.06x + .07y = .08z + 70

I assume the interest is 358.00, not 35800!

(x,y,z) = (1000,2200,1800)

Answer 2

If Muntaha were younger by 5 years than what she really is then the square of her age would have been 11 more than five times her actual age. What is her age now?