Question

A mother wants to invest $5,000.00 for her son's future education. She invests a portion of the money in a bank certificate of deposit (CD account) which earns 4% and the remainder in a savings bond that earns 7%. If the total interest earned after one year is $300.00, how much money was invested in the CD account?

Answer 1

let us say, the CD amount she invested is "c"
and the amount she invested in the savings bond is "s"

she invested a total of 5,000
so, whatever "c" is and "s" is, c + s = 5,000

now, the CD account earned 4% in interest
4% in decimal form is 4/100 or 0.04

she also earns 7% from the saving bonds,
7/100 is 0.07

the interest earned after one year are 300
that is, the 4% per year and the 7% per year add up to 300 bucks
so, one can say that

0.04c + 0.07s = 300


`\begin{cases} c+s=5,000\to s=\boxed{5,000-c} \\ \quad \\ 0.04c+0.07s=300\to 0.04c+0.07(\boxed{5,000-c})=300 \end{cases} \\ \quad \\ \textit{solve for`

Answer 2

1666.67

Explanation:

my math lab said it's 1666.67