let r = base interest rate as a decimal

$12000(r+.02) = 12000r + 240

$6000(r) = 6000r

18000r + 240 = 1050

solve for r ... remember it is the base interest rate in decimal form

Results 1 to 12 of 12

- Nov 1st 2008, 07:16 PM #1
## Hello, I need some help please

Question is:

Jack has $18000 to invest , he invests 2/3 in one account and the rest in the second account. The first account returned 2% more than the second account. The total return on his investment was $1050. What were the % rates of the two accounts.

Not sure if I'm doing it right cause I keep coming up with all sorts of answers that don't multiply to the end.

---------------------------------------

|P| |R| |I|

---------------------------------------

1st 12000 x (240+x)

---------------------------------------

2nd 18000-12000=6000 x

---------------------------------------

T= 18000 Interest saved 1050

---------------------------------------

18000* 2/3 = 12000

18000-12000= 6000

12000*.02 = 240

1050 -240 = 810

810:2 = 405

Did I set this up right? cause I keep coming up with 66.6 for x at 6000 and 33.3 for 12000

18000-6000 %

---------- = -------

18000 100

What am I doing wrong? just doesn't look right. Thank you for the help. This is just a 5 point extra credit for class. And, I already spent 2 days on this and I'm getting frustrated. When I go to times it all to see if it adds up it doesn't. Have to be missing something.

- Nov 1st 2008, 09:02 PM #2
let r = base interest rate as a decimal

$12000(r+.02) = 12000r + 240

$6000(r) = 6000r

18000r + 240 = 1050

solve for r ... remember it is the base interest rate in decimal form

- Nov 1st 2008, 09:34 PM #3

- Nov 1st 2008, 10:10 PM #4

- Nov 2nd 2008, 04:58 AM #5

- Nov 2nd 2008, 09:28 AM #6

- Nov 2nd 2008, 10:13 AM #7

- Nov 2nd 2008, 10:31 AM #8
but when you do the total like mutiply it across it doesn't add up

18000(.045)=1050 =810 probably be for the 6000 loan have to divide that by 2 you get 405 then you add the 240 to 405 you 625 for the 1200 loan

so then I would need to do it for 12000 to find that percent%

when you do the tic tac toe box doesn't it have to add down to 1050 and then multiply with everything across to add to 1050

that's how I've been doing it.

- Nov 2nd 2008, 10:39 AM #9

- Nov 2nd 2008, 11:26 AM #10

oh ok I forgot about the 2% maybe that's where I was messing up.

sorry for being a pain..

so when you add .065 +.045 you get .11 % as a total

12000 ----------------.065%---------------.065(240+540)=780

_______________________________________________

6000 18000-12000

=6000 ----.045%------------ 6000(.045)= 270

--------------------------------------------------------

Total= 18000--------------.11%----------------1050

Total=18000(.11)=1050

It add downs but it isn't multiplying across

Does not add up? Percent wise anyway, comes to 1980 and not 1050 When I mutiply across. That's what I mean. sorry... I don't know how to do the math computer code.

- Nov 2nd 2008, 11:43 AM #11so when you add .065 +.045 you get .11 % as a total
__do not__add the two percents ... one percent (6.5%) is applied only to the $12000, the other (4.5%) only applies to the remaining $6000.

if you want to find the "effective" total interest ...

%

you're done.

- Nov 2nd 2008, 12:31 PM #12