SOLUTION: a designer invest $20,000.0 in two CDs. the first CD pays 11% per annum simple interest, and the second pays 12.5%. at the end of on year she has earned 2320.0 in interest. * h

Question 718466: a designer invest $20,000.0 in two CDs. the first CD pays 11% per annum simple interest, and the second pays 12.5%. at the end of on year she has earned 2320.0 in interest.
* how much did she invest in each CD?
* what was the effective interest rate on the total investments?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
CD I 11.00% per annum ------------- Amount invested =x
CD II 12.50% per annum ------------ Amount invested = y
20000
Interest----- 2320

CD I 11.00% per annum ---x
CD II 12.50% per annum ---y
Total investment
x + 1 y= 20000 -------------1
Interest on both investments
11.00% x + 12.50% y= 2320
Multiply by 100
11 x + 12.5 y= 232000.00 --------2
Multiply (1) by -11
we get
-11 x -11 y= -220000.00
Add this to (2)
0 x 1.5 y= 12000
divide by 1.5
y = 8000
CD I 11.00% $ 12000
CD II 12.50% $ 8000

CHECK
12000 --------- 11.00% ------- 1320.00
8000 ------------- 12.50% ------- 1000.00
Total -------------------- 2320.00
20000----------2320
100----------?
100/20000 * 2320

11.6%
m.ananth@hotmail.ca

RELATED QUESTIONS
Nora invest $800 that pays simple interest at the rate of 6% per annum and $1,200 that... (answered by addingup,ikleyn)

Translate to a system of equations and solve. Mark wants to invest $10,000 to pay for... (answered by Boreal)

1. Ellen has $8000 to invest in an RESP (Registered Education Savings Plan) for 7 years.... (answered by josmiceli)

A total of $500,000 was invested into two accounts. One fund pays 5.2% and the second one (answered by Shin123)

You have $30,000 to invest in two stock funds. The first fund pays 5% annual (answered by ikleyn,greenestamps)

Tony has a total of 12,500 in two accounts. One account pays 2% simple interest per year... (answered by richwmiller)

Tony has a total of $12,500 in two accounts. One account pays 2% simple interest per year (answered by richwmiller)

1. Train A has a speed 20 miles per hour greater than that of train B. If train A travels (answered by ikleyn,greenestamps,josgarithmetic)

11. Gundeep invests a total of $5000 in two funds. One fund pays interest at 4% per... (answered by mananth)