Question

Mrs. Mary Moolah invested $20,000 in

Answer 1

Answer: the amount of money invested at the 5% rate is $15000

Step-by-step explanation:

Let x represent the amount of money invested at the rate of 5%.

Let y represent the amount of money invested at the rate of 8%.

Mrs. Mary Moolah invested $20,000 in two different types of bonds. This means that

x + y = 20000

The formula for simple interest is expressed as

I = PRT/100

Where

P represents the principal

R represents interest rate

T represents time

Considering the investment at the rate of 5%,

P = x

R = 5

T = 1

I = (x × 5 × 1)/100 = 0.05x

Considering the investment at the rate of 8%,

P = y

R = 8

T = 1

I = (y × 8 × 1)/100 = 0.08y

If Mrs. Moolah's combined profit from both investments was $1,150, it means that

0.05x + 0.08y = 1150 - - - - - -1

Substituting x = 20000 - y into equation 1, it becomes

0.05(20000 - y) + 0.08y = 1150

1000 - 0.05y + 0.08y = 1150

- 0.05y + 0.08y = 1150 - 1000

0.03y = 150

y = 150/0.03 = 5000

Substituting y = 5000 into x = 20000 - y, it becomes

x = 20000 - 5000

x = 15000