SOLUTION: a portion of $7000 is invested in a CD earning 4% and the remainder is in a savings bond earns 7%. if total interest earned after one year is $420, how much money was invested at e

Question 315672: a portion of $7000 is invested in a CD earning 4% and the remainder is in a savings bond earns 7%. if total interest earned after one year is $420, how much money was invested at each rate? What is the formula for this problem?
Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
There's no formula, you need to set up a linear system of equations.
Let A be the amount at 4%, B the amount at 7%.
The total amount invested,
1.
The interest received,

2.
Multiply eq. 1 by (-4) and add to eq. 2 to eliminate A and solve for B,

Then from eq. 1,

RELATED QUESTIONS
A mother wants to invest $11,000 for her son's future education. She invests a portion of (answered by scott8148)

A mother wants to invest $11,000.00 for her son's future education. She invests a portion (answered by mananth)

a mother invest $13,000.00 for her son's future education she invests a portion of the... (answered by richwmiller)

A mother wants to invest $10,000 for her son's future education. She invests a portion of (answered by Boreal)

A mother wants to invest $9,000.00 for her son's future education. She invests a portion... (answered by Boreal,josmiceli)

a mother wants to invest $5000 for their children's education. She invests a portion of... (answered by richwmiller)

A mother wants to invest $12000 for her children's education. She invests a portion of... (answered by mananth,nunezs1981)

A mother wants to invest $12,000 for her sons future education. She invests a portion of... (answered by rfer,mickclns)

Someone invested $12,000.00 for her education. The person invests a portion in a bank... (answered by checkley71)