Question

Rico invests some of his savings at 3 percent per year & an equal amount at 5 percent per year. His income totals 1,800 a year. How much did Rico invest at each rate?

Answer 1

`$22,500" "` at each rate.

Explanation:

The interest is earned over one year, so it does not matter whether it is invested at simple or compound interest.

Let the amount of money at each rate be `x`

`SI = (PRT)/100`

`(x xx 3 xx 1)/100 + (x xx 5xx 1)/100 = 1800`

Multiply by 100 to cancel the denominators.

`(color(blue)(100xx)x xx 3 xx 1)/100 + (color(blue)(100xx)x xx 5xx 1)/100 = color(blue)(100xx)1800`

`3x +5x = 180,000`

#8x = 180,000)

`x =$22,500`