SOLUTION: A mother wants to invest $12,000 for her sons future education. She invests a portion of the money into a bank CD which 4% and the remainder in a savings bond that earns 7%. If the

Question 206325: A mother wants to invest $12,000 for her sons future education. She invests a portion of the money into a bank CD which 4% and the remainder in a savings bond that earns 7%. If the total interest earned after one year is $720.00 how much was invested into the CD??
Found 2 solutions by rfer, mickclns:
Answer by rfer(16322) (Show Source): You can put this solution on YOUR website!
x=CD
12000-x=Bond
------------------
.04x+.07(12000-x)=720
.04x+840-.07x=720
-.03x=-120
x=4000
------------------
4000*.04+8000*.07=720
Answer by mickclns(59) (Show Source): You can put this solution on YOUR website!
Let c be the amount invested in the CD. The amount invested in a bond is $12,000 - c
The interest earned on the CD is .04c. The interest earned on the bond is .07(12000 - c).
The equation, then, for the total interest earned is:
.04c + .07(12000 - c) = 720
.04c + 840 - .07c = 720 Combining the terms with c in them and subtracting 840 from both sides:
-.03c = -120 Dividing both sides by -3, we have
.01c = 40 Multiplying both sides by 100 (same as dividing by .01 = 1/100), we have
c = 4000 which is the answer desired.
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 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 $6,000.00 for her son's future education. She invests a portion (answered by mananth)
A mother wants to invest 12,000.00 for her son's future education. She invests a portion... (answered by jorel1380)
can you please help me solve this word problem: A mother wants to invest $7,000.00 for... (answered by MathTherapy)
A mother wants to invest $10,000.00 for her son's future education. She... (answered by jorel1380)
A mother wants to invest $10,000.00 for her son's future education. She... (answered by greenestamps)