A mother wants to invest ​$11,000.00 for her​ son's future education. She invests a portion of the money in a bank certificate of deposit​

Question

A mother wants to invest ​$11,000.00 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 which earns​ 7%. If the total interest earned after one year was $660.00, how much money was invested in the CD​ account?

Answer 1

660/11000= .06= 6%

7-6 = 1

6-4 = 2

2/1 = 2 = twice as much invested at 7% as in 4%

2x +x = 11000

x = 11000/3 = $3666.67 invested at 4% with a CD

2x = $7,333.33 invested at 6%

Answer 2

Total invested C + B = $11,000 so C = 11000 - B

Total interest 0.04C + 0.07B = 0.04(11000 - B) + 0.07B = $660

440 - 0.04B + 0.07B = 660 → 0.3B = 220

B = $7,333.33 Bond

C = 11000 - B = 11000 - 7333 = $3,666.67 CD

Check:

CD $3,666.67(0.04) = $146.67 interest

SB $7,333.33(0.07) = $513.33 "

Total $660.00