Question

A total of $5000 is invested: part at 5% and the remainder at 15%. How much is invested at each rate if the annual interest is $720?

Answer 1

Answer:

At 5% , $300 was invested

At 15%, $4,700 was invested

Step-by-step explanation:

Let the amount invested at 5% be $x and the amount invested at 15% be $y

x + y = 5000 ••••••(i)

Let’s work with the interest;

5% of x + 15% of y = 720

0.05x + 0.15y = 720 •••••(ii)

From i;

x = 5000-y

Insert this into ii

0.05(5000-y) + 0.15y = 720

= 250 - 0.05y + 0.15y = 720

250 + 0.1y = 720

0.1y = 720-250

0.1y = 470

y = 470/0.1

y = $4700

x = 5000-y

x = 5000-4700 = $300