SOLUTION: A financial advisor invested a total of $10000 , part at 7.5% per annum compounded annually, part at 8% per annum compounded annually. At the end of the first year, a total of $780

Question 866234: A financial advisor invested a total of $10000 , part at 7.5% per annum compounded annually, part at 8% per annum compounded annually. At the end of the first year, a total of $780 interest had been earned. How much had been invested at each interest rate?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
Part I 7.50% per annum ------------- Amount invested =x
Part II 8.00% per annum ------------ Amount invested = y
10000
Interest----- 780.00

Part I 7.50% per annum ---x
Part II 8.00% per annum ---y
Total investment
x + 1 y= 10000 -------------1
Interest on both investments
7.50% x + 8.00% y= 780
Multiply by 100
7.5 x + 8 y= 78000.00 --------2
Multiply (1) by -7.5
we get
-7.5 x -7.5 y= -75000.00
Add this to (2)
0 x 0.5 y= 3000
divide by 0.5
y = 6000
Part I 7.50% $ 4000
Part II 8.00% $ 6000

CHECK
4000 --------- 7.50% ------- 300.00
6000 ------------- 8.00% ------- 480.00
Total -------------------- 780.00

m.ananth@hotmail.ca

RELATED QUESTIONS
A broker invested $10000, part earning interest at 8% per annum, and the remainder at 10% (answered by Boreal)

Tran has $10000 to invest. She invested part of it in a term deposit paying 4% per annum... (answered by stanbon)

sue had $10000 to invest. she invested part of it in a term deposit paying 4% per annum... (answered by macston)

A principal of $2500 is invested; part at 8% per annum and the rest at 12% per annum. In... (answered by checkley71)

Pete won $10 000 in a lottery. He invested his winnings, part at 10% per annum and part... (answered by checkley71)

1. Sajid has a goal of saving $20 000 in 8 years. What principal invested for 5 years at... (answered by josmiceli)

john invested 4000 for a year, part at 7% per annum and part at 9% per annum. the... (answered by Alan3354)

Mr.Thompson invests a principal of $8000; part at 8% per annum and the rest at 10% per... (answered by checkley71)

A certain sum invested at 4% per annum compounded semi-annually amounts to $7803 after... (answered by Theo)